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antoyo · 2021-05-31T13:38:44Z

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DR 2352 changed the definitions of reference-related (so that it uses "similar type" instead of "same type") and of reference-compatible (use a standard conversion sequence). That means that reference-related is now more broad, which means that we will be binding more things directly. The original patch for DR 2352 caused some problems, which were fixed in r276251 by creating a "fake" ck_qual in direct_reference_binding, so that in void f(int *); // #1 void f(const int * const &); // #2 int *x; int main() { f(x); // call #1 } we call #1. The extra ck_qual in #2 causes compare_ics to select #1, which is a better match for "int *" because then we don't have to do a qualification conversion. Let's turn to the problem in this PR. We have void f(const int * const &); // #1 void f(const int *); // #2 int *x; int main() { f(x); } We arrive in compare_ics to decide which one is better. The ICS for #1 looks like ck_ref_bind <- ck_qual <- ck_identity const int *const & const int *const int * and the ICS for #2 is ck_qual <- ck_rvalue <- ck_identity const int * int * int * We strip the reference and then comp_cv_qual_signature when comparing two ck_quals sees that "const int *" is a proper subset of "const int *const" and we return -1. But that's wrong; presumably the top-level "const" should be ignored and the call should be ambiguous. This patch adjust the type of the "fake" ck_qual so that this problem doesn't arise. PR c++/97296 gcc/cp/ChangeLog: * call.cc (direct_reference_binding): strip_top_quals when creating a ck_qual. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/ref-bind4.C: Add dg-error. * g++.dg/cpp0x/ref-bind8.C: New test.

Hi All, This patch adds initial support for early break vectorization in GCC. In other words it implements support for vectorization of loops with multiple exits. The support is added for any target that implements a vector cbranch optab, this includes both fully masked and non-masked targets. Depending on the operation, the vectorizer may also require support for boolean mask reductions using Inclusive OR/Bitwise AND. This is however only checked then the comparison would produce multiple statements. This also fully decouples the vectorizer's notion of exit from the existing loop infrastructure's exit. Before this patch the vectorizer always picked the natural loop latch connected exit as the main exit. After this patch the vectorizer is free to choose any exit it deems appropriate as the main exit. This means that even if the main exit is not countable (i.e. the termination condition could not be determined) we might still be able to vectorize should one of the other exits be countable. In such situations the loop is reflowed which enabled vectorization of many other loop forms. Concretely the kind of loops supported are of the forms: for (int i = 0; i < N; i++) { <statements1> if (<condition>) { ... <action>; } <statements2> } where <action> can be: - break - return - goto Any number of statements can be used before the <action> occurs. Since this is an initial version for GCC 14 it has the following limitations and features: - Only fixed sized iterations and buffers are supported. That is to say any vectors loaded or stored must be to statically allocated arrays with known sizes. N must also be known. This limitation is because our primary target for this optimization is SVE. For VLA SVE we can't easily do cross page iteraion checks. The result is likely to also not be beneficial. For that reason we punt support for variable buffers till we have First-Faulting support in GCC 15. - any stores in <statements1> should not be to the same objects as in <condition>. Loads are fine as long as they don't have the possibility to alias. More concretely, we block RAW dependencies when the intermediate value can't be separated fromt the store, or the store itself can't be moved. - Prologue peeling, alignment peelinig and loop versioning are supported. - Fully masked loops, unmasked loops and partially masked loops are supported - Any number of loop early exits are supported. - No support for epilogue vectorization. The only epilogue supported is the scalar final one. Peeling code supports it but the code motion code cannot find instructions to make the move in the epilog. - Early breaks are only supported for inner loop vectorization. With the help of IPA and LTO this still gets hit quite often. During bootstrap it hit rather frequently. Additionally TSVC s332, s481 and s482 all pass now since these are tests for support for early exit vectorization. This implementation does not support completely handling the early break inside the vector loop itself but instead supports adding checks such that if we know that we have to exit in the current iteration then we branch to scalar code to actually do the final VF iterations which handles all the code in <action>. For the scalar loop we know that whatever exit you take you have to perform at most VF iterations. For vector code we only case about the state of fully performed iteration and reset the scalar code to the (partially) remaining loop. That is to say, the first vector loop executes so long as the early exit isn't needed. Once the exit is taken, the scalar code will perform at most VF extra iterations. The exact number depending on peeling and iteration start and which exit was taken (natural or early). For this scalar loop, all early exits are treated the same. When we vectorize we move any statement not related to the early break itself and that would be incorrect to execute before the break (i.e. has side effects) to after the break. If this is not possible we decline to vectorize. The analysis and code motion also takes into account that it doesn't introduce a RAW dependency after the move of the stores. This means that we check at the start of iterations whether we are going to exit or not. During the analyis phase we check whether we are allowed to do this moving of statements. Also note that we only move the scalar statements, but only do so after peeling but just before we start transforming statements. With this the vector flow no longer necessarily needs to match that of the scalar code. In addition most of the infrastructure is in place to support general control flow safely, however we are punting this to GCC 15. Codegen: for e.g. unsigned vect_a[N]; unsigned vect_b[N]; unsigned test4(unsigned x) { unsigned ret = 0; for (int i = 0; i < N; i++) { vect_b[i] = x + i; if (vect_a[i] > x) break; vect_a[i] = x; } return ret; } We generate for Adv. SIMD: test4: adrp x2, .LC0 adrp x3, .LANCHOR0 dup v2.4s, w0 add x3, x3, :lo12:.LANCHOR0 movi v4.4s, 0x4 add x4, x3, 3216 ldr q1, [x2, #:lo12:.LC0] mov x1, 0 mov w2, 0 .p2align 3,,7 .L3: ldr q0, [x3, x1] add v3.4s, v1.4s, v2.4s add v1.4s, v1.4s, v4.4s cmhi v0.4s, v0.4s, v2.4s umaxp v0.4s, v0.4s, v0.4s fmov x5, d0 cbnz x5, .L6 add w2, w2, 1 str q3, [x1, x4] str q2, [x3, x1] add x1, x1, 16 cmp w2, 200 bne .L3 mov w7, 3 .L2: lsl w2, w2, 2 add x5, x3, 3216 add w6, w2, w0 sxtw x4, w2 ldr w1, [x3, x4, lsl 2] str w6, [x5, x4, lsl 2] cmp w0, w1 bcc .L4 add w1, w2, 1 str w0, [x3, x4, lsl 2] add w6, w1, w0 sxtw x1, w1 ldr w4, [x3, x1, lsl 2] str w6, [x5, x1, lsl 2] cmp w0, w4 bcc .L4 add w4, w2, 2 str w0, [x3, x1, lsl 2] sxtw x1, w4 add w6, w1, w0 ldr w4, [x3, x1, lsl 2] str w6, [x5, x1, lsl 2] cmp w0, w4 bcc .L4 str w0, [x3, x1, lsl 2] add w2, w2, 3 cmp w7, 3 beq .L4 sxtw x1, w2 add w2, w2, w0 ldr w4, [x3, x1, lsl 2] str w2, [x5, x1, lsl 2] cmp w0, w4 bcc .L4 str w0, [x3, x1, lsl 2] .L4: mov w0, 0 ret .p2align 2,,3 .L6: mov w7, 4 b .L2 and for SVE: test4: adrp x2, .LANCHOR0 add x2, x2, :lo12:.LANCHOR0 add x5, x2, 3216 mov x3, 0 mov w1, 0 cntw x4 mov z1.s, w0 index z0.s, #0, #1 ptrue p1.b, all ptrue p0.s, all .p2align 3,,7 .L3: ld1w z2.s, p1/z, [x2, x3, lsl 2] add z3.s, z0.s, z1.s cmplo p2.s, p0/z, z1.s, z2.s b.any .L2 st1w z3.s, p1, [x5, x3, lsl 2] add w1, w1, 1 st1w z1.s, p1, [x2, x3, lsl 2] add x3, x3, x4 incw z0.s cmp w3, 803 bls .L3 .L5: mov w0, 0 ret .p2align 2,,3 .L2: cntw x5 mul w1, w1, w5 cbz w5, .L5 sxtw x1, w1 sub w5, w5, #1 add x5, x5, x1 add x6, x2, 3216 b .L6 .p2align 2,,3 .L14: str w0, [x2, x1, lsl 2] cmp x1, x5 beq .L5 mov x1, x4 .L6: ldr w3, [x2, x1, lsl 2] add w4, w0, w1 str w4, [x6, x1, lsl 2] add x4, x1, 1 cmp w0, w3 bcs .L14 mov w0, 0 ret On the workloads this work is based on we see between 2-3x performance uplift using this patch. Follow up plan: - Boolean vectorization has several shortcomings. I've filed PR110223 with the bigger ones that cause vectorization to fail with this patch. - SLP support. This is planned for GCC 15 as for majority of the cases build SLP itself fails. This means I'll need to spend time in making this more robust first. Additionally it requires: * Adding support for vectorizing CFG (gconds) * Support for CFG to differ between vector and scalar loops. Both of which would be disruptive to the tree and I suspect I'll be handling fallouts from this patch for a while. So I plan to work on the surrounding building blocks first for the remainder of the year. Additionally it also contains reduced cases from issues found running over various codebases. Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. Also regtested with: -march=armv8.3-a+sve -march=armv8.3-a+nosve -march=armv9-a -mcpu=neoverse-v1 -mcpu=neoverse-n2 Bootstrapped Regtested x86_64-pc-linux-gnu and no issues. Bootstrap and Regtest on arm-none-linux-gnueabihf and no issues. gcc/ChangeLog: * tree-if-conv.cc (idx_within_array_bound): Expose. * tree-vect-data-refs.cc (vect_analyze_early_break_dependences): New. (vect_analyze_data_ref_dependences): Use it. * tree-vect-loop-manip.cc (vect_iv_increment_position): New. (vect_set_loop_controls_directly, vect_set_loop_condition_partial_vectors, vect_set_loop_condition_partial_vectors_avx512, vect_set_loop_condition_normal): Support multiple exits. (slpeel_tree_duplicate_loop_to_edge_cfg): Support LCSAA peeling for multiple exits. (slpeel_can_duplicate_loop_p): Change vectorizer from looking at BB count and instead look at loop shape. (vect_update_ivs_after_vectorizer): Drop asserts. (vect_gen_vector_loop_niters_mult_vf): Support peeled vector iterations. (vect_do_peeling): Support multiple exits. (vect_loop_versioning): Likewise. * tree-vect-loop.cc (_loop_vec_info::_loop_vec_info): Initialise early_breaks. (vect_analyze_loop_form): Support loop flows with more than single BB loop body. (vect_create_loop_vinfo): Support niters analysis for multiple exits. (vect_analyze_loop): Likewise. (vect_get_vect_def): New. (vect_create_epilog_for_reduction): Support early exit reductions. (vectorizable_live_operation_1): New. (find_connected_edge): New. (vectorizable_live_operation): Support early exit live operations. (move_early_exit_stmts): New. (vect_transform_loop): Use it. * tree-vect-patterns.cc (vect_init_pattern_stmt): Support gcond. (vect_recog_bitfield_ref_pattern): Support gconds and bools. (vect_recog_gcond_pattern): New. (possible_vector_mask_operation_p): Support gcond masks. (vect_determine_mask_precision): Likewise. (vect_mark_pattern_stmts): Set gcond def type. (can_vectorize_live_stmts): Force early break inductions to be live. * tree-vect-stmts.cc (vect_stmt_relevant_p): Add relevancy analysis for early breaks. (vect_mark_stmts_to_be_vectorized): Process gcond usage. (perm_mask_for_reverse): Expose. (vectorizable_comparison_1): New. (vectorizable_early_exit): New. (vect_analyze_stmt): Support early break and gcond. (vect_transform_stmt): Likewise. (vect_is_simple_use): Likewise. (vect_get_vector_types_for_stmt): Likewise. * tree-vectorizer.cc (pass_vectorize::execute): Update exits for value numbering. * tree-vectorizer.h (enum vect_def_type): Add vect_condition_def. (LOOP_VINFO_EARLY_BREAKS, LOOP_VINFO_EARLY_BRK_STORES, LOOP_VINFO_EARLY_BREAKS_VECT_PEELED, LOOP_VINFO_EARLY_BRK_DEST_BB, LOOP_VINFO_EARLY_BRK_VUSES): New. (is_loop_header_bb_p): Drop assert. (class loop): Add early_breaks, early_break_stores, early_break_dest_bb, early_break_vuses. (vect_iv_increment_position, perm_mask_for_reverse, ref_within_array_bound): New. (slpeel_tree_duplicate_loop_to_edge_cfg): Update for early breaks.

This patch adjusts the costs so that we treat REG and SUBREG expressions the same for costing. This was motivated by bt_skip_func and bt_find_func in xz and results in nearly a 5% improvement in the dynamic instruction count for input #2 and smaller, but definitely visible improvements pretty much across the board. Exceptions would be perlbench input #1 and exchange2 which showed very small regressions. In the bt_find_func and bt_skip_func cases we have something like this: > (insn 10 7 11 2 (set (reg/v:DI 136 [ x ]) > (zero_extend:DI (subreg/s/u:SI (reg/v:DI 137 [ a ]) 0))) "zz.c":6:21 387 {*zero_extendsidi2_bitmanip} > (nil)) > (insn 11 10 12 2 (set (reg:DI 142 [ _1 ]) > (plus:DI (reg/v:DI 136 [ x ]) > (reg/v:DI 139 [ b ]))) "zz.c":7:23 5 {adddi3} > (nil)) [ ... ]> (insn 13 12 14 2 (set (reg:DI 143 [ _2 ]) > (plus:DI (reg/v:DI 136 [ x ]) > (reg/v:DI 141 [ c ]))) "zz.c":8:23 5 {adddi3} > (nil)) Note the two uses of (reg 136). The best way to handle that in combine might be a 3->2 split. But there's a much better approach if we look at fwprop... (set (reg:DI 142 [ _1 ]) (plus:DI (zero_extend:DI (subreg/s/u:SI (reg/v:DI 137 [ a ]) 0)) (reg/v:DI 139 [ b ]))) change not profitable (cost 4 -> cost 8) So that should be the same cost as a regular DImode addition when the ZBA extension is enabled. But it ends up costing more because the clause to cost this variant isn't prepared to handle a SUBREG. That results in the RTL above having too high a cost and fwprop gives up. One approach would be to replace the REG_P with REG_P || SUBREG_P in the costing code. I ultimately decided against that and instead check if the operand in question passes register_operand. By far the most important case to handle is the DImode PLUS. But for the sake of consistency, I changed the other instances in riscv_rtx_costs as well. For those other cases we're talking about improvements in the .000001% range. While we are into stage4, this just hits cost modeling which we've generally agreed is still appropriate (though we were mostly talking about vector). So I'm going to extend that general agreement ever so slightly and include scalar cost modeling :-) gcc/ * config/riscv/riscv.cc (riscv_rtx_costs): Handle SUBREG and REG similarly. gcc/testsuite/ * gcc.target/riscv/reg_subreg_costs.c: New test. Co-authored-by: Jivan Hakobyan <[email protected]>

Implement vddup and vidup using the new MVE builtins framework. We generate better code because we take advantage of the two outputs produced by the v[id]dup instructions. For instance, before: ldr r3, [r0] sub r2, r3, #8 str r2, [r0] mov r2, r3 vddup.u16 q3, r2, #1 now: ldr r2, [r0] vddup.u16 q3, r2, #1 str r2, [r0] 2024-08-21 Christophe Lyon <[email protected]> gcc/ * config/arm/arm-mve-builtins-base.cc (class viddup_impl): New. (vddup): New. (vidup): New. * config/arm/arm-mve-builtins-base.def (vddupq): New. (vidupq): New. * config/arm/arm-mve-builtins-base.h (vddupq): New. (vidupq): New. * config/arm/arm_mve.h (vddupq_m): Delete. (vddupq_u8): Delete. (vddupq_u32): Delete. (vddupq_u16): Delete. (vidupq_m): Delete. (vidupq_u8): Delete. (vidupq_u32): Delete. (vidupq_u16): Delete. (vddupq_x_u8): Delete. (vddupq_x_u16): Delete. (vddupq_x_u32): Delete. (vidupq_x_u8): Delete. (vidupq_x_u16): Delete. (vidupq_x_u32): Delete. (vddupq_m_n_u8): Delete. (vddupq_m_n_u32): Delete. (vddupq_m_n_u16): Delete. (vddupq_m_wb_u8): Delete. (vddupq_m_wb_u16): Delete. (vddupq_m_wb_u32): Delete. (vddupq_n_u8): Delete. (vddupq_n_u32): Delete. (vddupq_n_u16): Delete. (vddupq_wb_u8): Delete. (vddupq_wb_u16): Delete. (vddupq_wb_u32): Delete. (vidupq_m_n_u8): Delete. (vidupq_m_n_u32): Delete. (vidupq_m_n_u16): Delete. (vidupq_m_wb_u8): Delete. (vidupq_m_wb_u16): Delete. (vidupq_m_wb_u32): Delete. (vidupq_n_u8): Delete. (vidupq_n_u32): Delete. (vidupq_n_u16): Delete. (vidupq_wb_u8): Delete. (vidupq_wb_u16): Delete. (vidupq_wb_u32): Delete. (vddupq_x_n_u8): Delete. (vddupq_x_n_u16): Delete. (vddupq_x_n_u32): Delete. (vddupq_x_wb_u8): Delete. (vddupq_x_wb_u16): Delete. (vddupq_x_wb_u32): Delete. (vidupq_x_n_u8): Delete. (vidupq_x_n_u16): Delete. (vidupq_x_n_u32): Delete. (vidupq_x_wb_u8): Delete. (vidupq_x_wb_u16): Delete. (vidupq_x_wb_u32): Delete. (__arm_vddupq_m_n_u8): Delete. (__arm_vddupq_m_n_u32): Delete. (__arm_vddupq_m_n_u16): Delete. (__arm_vddupq_m_wb_u8): Delete. (__arm_vddupq_m_wb_u16): Delete. (__arm_vddupq_m_wb_u32): Delete. (__arm_vddupq_n_u8): Delete. (__arm_vddupq_n_u32): Delete. (__arm_vddupq_n_u16): Delete. (__arm_vidupq_m_n_u8): Delete. (__arm_vidupq_m_n_u32): Delete. (__arm_vidupq_m_n_u16): Delete. (__arm_vidupq_n_u8): Delete. (__arm_vidupq_m_wb_u8): Delete. (__arm_vidupq_m_wb_u16): Delete. (__arm_vidupq_m_wb_u32): Delete. (__arm_vidupq_n_u32): Delete. (__arm_vidupq_n_u16): Delete. (__arm_vidupq_wb_u8): Delete. (__arm_vidupq_wb_u16): Delete. (__arm_vidupq_wb_u32): Delete. (__arm_vddupq_wb_u8): Delete. (__arm_vddupq_wb_u16): Delete. (__arm_vddupq_wb_u32): Delete. (__arm_vddupq_x_n_u8): Delete. (__arm_vddupq_x_n_u16): Delete. (__arm_vddupq_x_n_u32): Delete. (__arm_vddupq_x_wb_u8): Delete. (__arm_vddupq_x_wb_u16): Delete. (__arm_vddupq_x_wb_u32): Delete. (__arm_vidupq_x_n_u8): Delete. (__arm_vidupq_x_n_u16): Delete. (__arm_vidupq_x_n_u32): Delete. (__arm_vidupq_x_wb_u8): Delete. (__arm_vidupq_x_wb_u16): Delete. (__arm_vidupq_x_wb_u32): Delete. (__arm_vddupq_m): Delete. (__arm_vddupq_u8): Delete. (__arm_vddupq_u32): Delete. (__arm_vddupq_u16): Delete. (__arm_vidupq_m): Delete. (__arm_vidupq_u8): Delete. (__arm_vidupq_u32): Delete. (__arm_vidupq_u16): Delete. (__arm_vddupq_x_u8): Delete. (__arm_vddupq_x_u16): Delete. (__arm_vddupq_x_u32): Delete. (__arm_vidupq_x_u8): Delete. (__arm_vidupq_x_u16): Delete. (__arm_vidupq_x_u32): Delete.

gcc.dg/torture/pr112305.c contains an inner loop that executes 0x8000_0014 times and an outer loop that executes 5 times, giving about 10 billion total executions of the inner loop body. At -O2 and above we are able to remove the inner loop, but at -O1 we keep a no-op loop: dls lr, r3 .L3: subs r3, r3, #1 le lr, .L3 and at -O0 we of course don't optimise. This can lead to long execution times on simulators, possibly triggering a timeout. gcc/testsuite * gcc.dg/torture/pr112305.c: Skip at -O0 and -O1 for simulators.

We currently crash upon the following invalid code (notice the "void void**" parameter) === cut here === using size_t = decltype(sizeof(int)); void *operator new(size_t, void void **p) noexcept { return p; } int x; void f() { int y; new (&y) int(x); } === cut here === The problem is that in this case, we end up with a NULL_TREE parameter list for the new operator because of the error, and (1) coerce_new_type wrongly complains about the first parameter type not being size_t, (2) std_placement_new_fn_p blindly accesses the parameter list, hence a crash. This patch does NOT address #1 since we can't easily distinguish between a new operator declaration without parameters from one with erroneous parameters (and it's not worth the risk to refactor and break things for an error recovery issue) hence a dg-bogus in new52.C, but it does address #2 and the ICE by simply checking the first parameter against NULL_TREE. It also adds a new testcase checking that we complain about new operators with no or invalid first parameters, since we did not have any. PR c++/117101 gcc/cp/ChangeLog: * init.cc (std_placement_new_fn_p): Check first_arg against NULL_TREE. gcc/testsuite/ChangeLog: * g++.dg/init/new52.C: New test. * g++.dg/init/new53.C: New test.

Update test case for armv8.1-m.main that supports conditional arithmetic. armv7-m: push {r4, lr} ldr r4, .L6 ldr r4, [r4] lsls r4, r4, #29 it mi addmi r2, r2, #1 bl bar movs r0, #0 pop {r4, pc} armv8.1-m.main: push {r3, r4, r5, lr} ldr r4, .L5 ldr r5, [r4] tst r5, #4 csinc r2, r2, r2, eq bl bar movs r0, #0 pop {r3, r4, r5, pc} gcc/testsuite/ChangeLog: * gcc.target/arm/epilog-1.c: Use check-function-bodies. Signed-off-by: Torbjörn SVENSSON <[email protected]>

The second source register of insn "*extzvsi-1bit_addsubx" cannot be the same as the destination register, because that register will be overwritten with an intermediate value after insn splitting. /* example #1 */ int test1(int b, int a) { return ((a & 1024) ? 4 : 0) + b; } ;; result #1 (incorrect) test1: extui a2, a3, 10, 1 ;; overwrites A2 before used addx4 a2, a2, a2 ret.n This patch fixes that. ;; result #1 (correct) test1: extui a3, a3, 10, 1 ;; uses A3 and then overwrites addx4 a2, a3, a2 ret.n However, it should be noted that the first source register can be the same as the destination without any problems. /* example #2 */ int test2(int a, int b) { return ((a & 1024) ? 4 : 0) + b; } ;; result (correct) test2: extui a2, a2, 10, 1 ;; uses A2 and then overwrites addx4 a2, a2, a3 ret.n gcc/ChangeLog: * config/xtensa/xtensa.md (*extzvsi-1bit_addsubx): Add '&' to the destination register constraint to indicate that it is 'earlyclobber', append '0' to the first source register constraint to indicate that it can be the same as the destination register, and change the split condition from 1 to reload_completed so that the insn will be split only after RA in order to obtain allocated registers that satisfy the above constraints.

vec.h has this method: template<typename T, typename A> inline T * vec_safe_push (vec<T, A, vl_embed> *&v, const T &obj CXX_MEM_STAT_INFO) where v is a reference to a pointer to vec. This matches the regex for VecPrinter, so gdbhooks.py attempts to print it but chokes on the reference. I see the following: rust-lang#1 0x0000000002b84b7b in vec_safe_push<edge_def*, va_gc> (v=Traceback (most recent call last): File "$SRC/gcc/gcc/gdbhooks.py", line 486, in to_string return '0x%x' % intptr(self.gdbval) File "$SRC/gcc/gcc/gdbhooks.py", line 168, in intptr return long(gdbval) if sys.version_info.major == 2 else int(gdbval) gdb.error: Cannot convert value to long. This patch makes VecPrinter handle such references by stripping them (dereferencing) at the top of the relevant functions. gcc/ChangeLog: * gdbhooks.py (strip_ref): New. Use it ... (VecPrinter.to_string): ... here, (VecPrinter.children): ... and here.

Brief: The bug appears in LRA after rematerialization pass while creating live ranges. File lra.cc: ************************************************************* /* Now we know what pseudos should be spilled. Try to rematerialize them first. */ if (lra_remat ()) { /* We need full live info -- see the comment above. */ lra_create_live_ranges (lra_reg_spill_p, true); ************************************************************* Wrong call `lra_create_live_ranges (lra_reg_spill_p, true)' It have to be `lra_create_live_ranges (true, true)'. The explanation: ********************************** int main (void) { if (a.u33 * a.u33 != 0) ------^^^^^^^^^^^^^ goto abrt; if (a.u33 * a.u40 * a.u33 != 0) ********************************** The bug appears here. Part of the expression `a.u33 * a.u33' Before LRA: ************************************************************* (insn 13 11 15 2 (set (reg:QI 184 [ _1+3 ]) (mem/c:QI (const:HI (plus:HI (symbol_ref:HI ("a") [flags 0x2] <var_decl 0x7c866435d000 a>) (const_int 3 [0x3]))) [1 a+3 S1 A8])) "bf.c":11:8 86 {movqi_insn_split} (nil)) (insn 15 13 16 2 (set (reg:QI 64 [ a+4 ]) (mem/c:QI (const:HI (plus:HI (symbol_ref:HI ("a") [flags 0x2] <var_decl 0x7c866435d000 a>) (const_int 4 [0x4]))) [1 a+4 S1 A8])) "bf.c":11:8 86 {movqi_insn_split} (nil)) (insn 16 15 20 2 (set (reg:QI 185 [ _1+4 ]) (zero_extract:QI (reg:QI 64 [ a+4 ]) (const_int 1 [0x1]) (const_int 0 [0]))) "bf.c":11:8 985 {*extzvqi_split} (nil)) ************************************************************* After LRA: ************************************************************* (insn 587 11 13 2 (set (reg:QI 24 r24 [368]) (mem/c:QI (const:HI (plus:HI (symbol_ref:HI ("a") [flags 0x2] <var_decl 0x7c866435d000 a>) (const_int 3 [0x3]))) [1 a+3 S1 A8])) "bf.c":11:8 86 {movqi_insn_split} (nil)) (insn 13 587 15 2 (set (mem/c:QI (plus:HI (reg/f:HI 28 r28) (const_int 1 [0x1])) [4 %sfp+1 S1 A8]) (reg:QI 24 r24 [368])) "bf.c":11:8 86 {movqi_insn_split} (nil)) (insn 15 13 16 2 (set (reg:QI 6 r6 [orig:64 a+4 ] [64]) (mem/c:QI (const:HI (plus:HI (symbol_ref:HI ("a") [flags 0x2] <var_decl 0x7c866435d000 a>) (const_int 4 [0x4]))) [1 a+4 S1 A8])) "bf.c":11:8 86 {movqi_insn_split} (nil)) (insn 16 15 572 2 (set (reg:QI 24 r24 [orig:185 _1+4 ] [185]) (zero_extract:QI (reg:QI 6 r6 [orig:64 a+4 ] [64]) (const_int 1 [0x1]) (const_int 0 [0]))) "bf.c":11:8 985 {*extzvqi_split} (nil)) (insn 572 16 20 2 (set (mem/c:QI (plus:HI (reg/f:HI 28 r28) (const_int 1 [0x1])) [4 %sfp+1 S1 A8]) (reg:QI 24 r24 [orig:185 _1+4 ] [185])) "bf.c":11:8 86 {movqi_insn_split} (nil)) ************************************************************* Insn 13 and insn 572 use sfp+1 as a spill slot, but in IRA pass it was a two different pseudos r184 and r185. Insns 13 use sfp+1 as a spill slot for r184 Insns 572 use the same slot for r185. It's wrong. Here we have a rematerialization. Fragment from bf.c.317r.reload: ************************************************************************************** ******** Rematerialization rust-lang#1: ******** df_worklist_dataflow_doublequeue: n_basic_blocks 14 n_edges 18 count 14 ( 1) df_worklist_dataflow_doublequeue: n_basic_blocks 14 n_edges 18 count 14 ( 1) Cands: 0 (nop=0, remat_regno=185, reload_regno=359): (insn 16 15 572 2 (set (reg:QI 359 [orig:185 _1+4 ] [185]) (zero_extract:QI (reg:QI 64 [ a+4 ]) (const_int 1 [0x1]) (const_int 0 [0]))) "bf.c":11:8 985 {*extzvqi_split} (nil)) ************************************************************************************** [...] ************************************************************************************** Ranges after the compression: r185: [0..1] Frame pointer can not be eliminated anymore Spilling non-eliminable hard regs: 28 29 Spilling r113(28) Spilling r184(29) Spilling r208(29) Spilling r209(28) Slot 0 regnos (width = 0): 185 209 208 184 113 ************************************************************************************** The bug is here: `r185: [0..1]' wrong live range after compression. r185 and r184 can't have the same spill slot ! Rematerialization in bf.c.317r.reload looks like: ************************************************************* 24: r14:QI=r185:QI Inserting rematerialization insn before: 581: r14:QI=zero_extract(r64:QI,0x1,0) deleting insn with uid = 24. Considering alt=0 of insn 16: (0) =r (1) rYil (2) n overall=0,losers=0,rld_nregs=0 32: r22:QI=r185:QI Inserting rematerialization insn before: 582: r22:QI=zero_extract(r64:QI,0x1,0) deleting insn with uid = 32. ************************************************************* It's happened because: Fragment from lra.c (lra): ************************************************************************* if (! live_p) { /* We need full live info for spilling pseudos into registers instead of memory. */ lra_create_live_ranges (lra_reg_spill_p, true); live_p = true; } /* We should check necessity for spilling here as the above live range pass can remove spilled pseudos. */ if (! lra_need_for_spills_p ()) break; /* Now we know what pseudos should be spilled. Try to rematerialize them first. */ if (lra_remat ()) { /* We need full live info -- see the comment above. */ lra_create_live_ranges (lra_reg_spill_p, true); ----------------------------------^^^^^^^^^^^^^^^ live_p = true; ************************************************************************* The bug is here. Rematerialization sometimes can be like spilling pseudos into registers. 582: r22:QI=zero_extract(r64:QI,0x1,0) So, here we need a live ranges for all pseudos. PS: the patch will not affect any target with usable definition of TARGET_SPILL_CLASS hook. PR target/116778 gcc/ * lra-lives.cc (complete_info_p): Clarification of the comment. * lra.cc (lra): Create a full live info after rematerialization.

This PR reports a missed optimization. When we have: Str str{"Test"}; callback(str); as in the test, we're able to evaluate the Str::Str() call at compile time. But when we have: callback(Str{"Test"}); we are not. With this patch (in fact, it's Patrick's patch with a little tweak), we turn callback (TARGET_EXPR <D.2890, <<< Unknown tree: aggr_init_expr 5 __ct_comp D.2890 (struct Str *) <<< Unknown tree: void_cst >>> (const char *) "Test" >>>>) into callback (TARGET_EXPR <D.2890, {.str=(const char *) "Test", .length=4}>) I explored the idea of calling maybe_constant_value for the whole TARGET_EXPR in cp_fold. That has three problems: - we can't always elide a TARGET_EXPR, so we'd have to make sure the result is also a TARGET_EXPR; - the resulting TARGET_EXPR must have the same flags, otherwise Bad Things happen; - getting a new slot is also problematic. I've seen a test where we had "TARGET_EXPR<D.2680, ...>, D.2680", and folding the whole TARGET_EXPR would get us "TARGET_EXPR<D.2681, ...>", but since we don't see the outer D.2680, we can't replace it with D.2681, and things break. With this patch, two tree-ssa tests regressed: pr78687.C and pr90883.C. FAIL: g++.dg/tree-ssa/pr90883.C scan-tree-dump dse1 "Deleted redundant store: .*.a = {}" is easy. Previously, we would call C::C, so .gimple has: D.2590 = {}; C::C (&D.2590); D.2597 = D.2590; return D.2597; Then .einline inlines the C::C call: D.2590 = {}; D.2590.a = {}; // rust-lang#1 D.2590.b = 0; // rust-lang#2 D.2597 = D.2590; D.2590 ={v} {CLOBBER(eos)}; return D.2597; then rust-lang#2 is removed in .fre1, and rust-lang#1 is removed in .dse1. So the test passes. But with the patch, .gimple won't have that C::C call, so the IL is of course going to look different. The .optimized dump looks the same though so there's no problem. pr78687.C is XFAILed because the test passes with r15-5746 but not with r15-5747 as well. I opened <https://gcc.gnu.org/PR117971>. PR c++/116416 gcc/cp/ChangeLog: * cp-gimplify.cc (cp_fold_r) <case TARGET_EXPR>: Try to fold TARGET_EXPR_INITIAL and replace it with the folded result if it's TREE_CONSTANT. gcc/testsuite/ChangeLog: * g++.dg/analyzer/pr97116.C: Adjust dg-message. * g++.dg/tree-ssa/pr78687.C: Add XFAIL. * g++.dg/tree-ssa/pr90883.C: Adjust dg-final. * g++.dg/cpp0x/constexpr-prvalue1.C: New test. * g++.dg/cpp1y/constexpr-prvalue1.C: New test. Co-authored-by: Patrick Palka <[email protected]> Reviewed-by: Jason Merrill <[email protected]>

@far

With the changes in r15-1579-g792f97b44ff, the code used as "padding" in the test case is optimized way. Prevent this optimization by forcing a read of the volatile memory. Also, validate that there is a far jump in the generated assembler. Without this patch, the generated assembler is reduced to: f3: cmp r0, #0 beq .L1 ldr r4, .L6 .L1: bx lr .L7: .align 2 .L6: .word g_0_1 With the patch, the generated assembler is: f3: movs r2, rust-lang#1 ldr r3, .L6 push {lr} str r2, [r3] cmp r0, #0 bne .LCB10 bl .L1 @far jump .LCB10: b .L7 .L8: .align 2 .L6: .word .LANCHOR0 .L7: str r2, [r3] ... str r2, [r3] .L1: pop {pc} gcc/testsuite/ChangeLog: * gcc.target/arm/thumb1-far-jump-2.c: Write to volatile memmory in macro to avoid optimization. Signed-off-by: Torbjörn SVENSSON <[email protected]>

On Cortex-M4, the code generated is: cmp r0, r1 itte ne lslne r0, r0, r1 asrne r0, r0, rust-lang#1 moveq r0, r1 add r0, r0, r1 bx lr On Cortex-M7, the code generated is: cmp r0, r1 beq .L3 lsls r0, r0, r1 asrs r0, r0, rust-lang#1 add r0, r0, r1 bx lr .L3: mov r0, r1 add r0, r0, r1 bx lr As Cortex-M7 only allow maximum one conditional instruction, force Cortex-M4 to have a stable test case. gcc/testsuite/ChangeLog: * gcc.target/arm/thumb-ifcvt.c: Use -mtune=cortex-m4. Signed-off-by: Torbjörn SVENSSON <[email protected]>

This crash started with my r12-7803 but I believe the problem lies elsewhere. build_vec_init has cleanup_flags whose purpose is -- if I grok this correctly -- to avoid destructing an object multiple times. Let's say we are initializing an array of A. Then we might end up in a scenario similar to initlist-eh1.C: try { call A::A in a loop // #0 try { call a fn using the array } finally { // rust-lang#1 call A::~A in a loop } } catch { // rust-lang#2 call A::~A in a loop } cleanup_flags makes us emit a statement like D.3048 = 2; at #0 to disable performing the cleanup at rust-lang#2, since rust-lang#1 will take care of the destruction of the array. But if we are not emitting the loop because we can use a constant initializer (and use a single { a, b, ...}), we shouldn't generate the statement resetting the iterator to its initial value. Otherwise we crash in gimplify_var_or_parm_decl because it gets the stray decl D.3048. PR c++/117985 gcc/cp/ChangeLog: * init.cc (build_vec_init): Pop CLEANUP_FLAGS if we're not generating the loop. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/initlist-array23.C: New test. * g++.dg/cpp0x/initlist-array24.C: New test.

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antoyo force-pushed the build-artifact branch from b5d7f92 to c54e069 Compare May 31, 2021 16:05

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