[IR] Convert from nocapture to captures(none) (#123181)

This PR removes the old `nocapture` attribute, replacing it with the new
`captures` attribute introduced in #116990. This change is
intended to be essentially NFC, replacing existing uses of `nocapture`
with `captures(none)` without adding any new analysis capabilities.
Making use of non-`none` values is left for a followup.

Some notes:
* `nocapture` will be upgraded to `captures(none)` by the bitcode
   reader.
* `nocapture` will also be upgraded by the textual IR reader. This is to
   make it easier to use old IR files and somewhat reduce the test churn in
   this PR.
* Helper APIs like `doesNotCapture()` will check for `captures(none)`.
* MLIR import will convert `captures(none)` into an `llvm.nocapture`
   attribute. The representation in the LLVM IR dialect should be updated
   separately.

Author: nikic

clang/lib/CodeGen/CGCall.cpp

@@ -2881,7 +2881,7 @@ void CodeGenModule::ConstructAttributeList(StringRef Name,
     }
 
     if (FI.getExtParameterInfo(ArgNo).isNoEscape())
-      Attrs.addAttribute(llvm::Attribute::NoCapture);
+      Attrs.addCapturesAttr(llvm::CaptureInfo::none());
 
     if (Attrs.hasAttributes()) {
       unsigned FirstIRArg, NumIRArgs;

clang/lib/CodeGen/CGObjCGNU.cpp

@@ -773,7 +773,9 @@ class CGObjCGNUstep : public CGObjCGNU {
 
       // The lookup function is guaranteed not to capture the receiver pointer.
       if (auto *LookupFn2 = dyn_cast<llvm::Function>(LookupFn.getCallee()))
-        LookupFn2->addParamAttr(0, llvm::Attribute::NoCapture);
+        LookupFn2->addParamAttr(
+            0, llvm::Attribute::getWithCaptureInfo(CGF.getLLVMContext(),
+                                                   llvm::CaptureInfo::none()));
 
       llvm::Value *args[] = {
           EnforceType(Builder, ReceiverPtr.getPointer(), PtrToIdTy),

clang/test/CodeGen/AArch64/pure-scalable-args.c

@@ -67,7 +67,7 @@ void test_argpass_simple(PST *p) {
     void argpass_simple_callee(PST);
     argpass_simple_callee(*p);
 }
-// CHECK-AAPCS:      define dso_local void @test_argpass_simple(ptr nocapture noundef readonly %p)
+// CHECK-AAPCS:      define dso_local void @test_argpass_simple(ptr noundef readonly captures(none) %p)
 // CHECK-AAPCS-NEXT: entry:
 // CHECK-AAPCS-NEXT: %0 = load <2 x i8>, ptr %p, align 16
 // CHECK-AAPCS-NEXT: %cast.scalable = tail call <vscale x 2 x i8> @llvm.vector.insert.nxv2i8.v2i8(<vscale x 2 x i8> poison, <2 x i8> %0, i64 0)
@@ -292,24 +292,24 @@ PST test_return(PST *p) {
     return *p;
 }
 // CHECK-AAPCS:  define dso_local <{ <vscale x 16 x i1>, <vscale x 2 x double>, <vscale x 4 x float>, <vscale x 4 x float>, <vscale x 16 x i8>, <vscale x 16 x i1> }> @test_return(ptr
-// CHECK-DARWIN: define void @test_return(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.PST) align 16 initializes((0, 96)) %agg.result, ptr nocapture noundef readonly %p)
+// CHECK-DARWIN: define void @test_return(ptr dead_on_unwind noalias writable writeonly sret(%struct.PST) align 16 captures(none) initializes((0, 96)) %agg.result, ptr noundef readonly captures(none) %p)
 
 // Corner case of 1-element aggregate
 //   p->x -> q0
 SmallPST test_return_small_pst(SmallPST *p) {
     return *p;
 }
 // CHECK-AAPCS:  define dso_local <vscale x 4 x float> @test_return_small_pst(ptr
-// CHECK-DARWIN: define i128 @test_return_small_pst(ptr nocapture noundef readonly %p)
+// CHECK-DARWIN: define i128 @test_return_small_pst(ptr noundef readonly captures(none) %p)
 
 
 // Big PST, returned indirectly
 //   *p -> *x8
 BigPST test_return_big_pst(BigPST *p) {
     return *p;
 }
-// CHECK-AAPCS:  define dso_local void @test_return_big_pst(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.BigPST) align 16 initializes((0, 176)) %agg.result, ptr nocapture noundef readonly %p)
-// CHECK-DARWIN: define void @test_return_big_pst(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.BigPST) align 16 initializes((0, 176)) %agg.result, ptr nocapture noundef readonly %p)
+// CHECK-AAPCS:  define dso_local void @test_return_big_pst(ptr dead_on_unwind noalias writable writeonly sret(%struct.BigPST) align 16 captures(none) initializes((0, 176)) %agg.result, ptr noundef readonly captures(none) %p)
+// CHECK-DARWIN: define void @test_return_big_pst(ptr dead_on_unwind noalias writable writeonly sret(%struct.BigPST) align 16 captures(none) initializes((0, 176)) %agg.result, ptr noundef readonly captures(none) %p)
 
 // Variadic arguments are unnamed, PST passed indirectly.
 // (Passing SVE types to a variadic function currently unsupported by

clang/test/CodeGen/AArch64/sve-acle-__ARM_FEATURE_SVE_VECTOR_OPERATORS.c

@@ -59,7 +59,7 @@ typedef int8_t vec_int8 __attribute__((vector_size(N / 8)));
 // CHECK128-NEXT:    ret <16 x i8> [[CASTFIXEDSVE]]
 
 // CHECK-LABEL: define{{.*}} void @f2(
-// CHECK-SAME:   ptr dead_on_unwind noalias nocapture writable writeonly sret(<[[#div(VBITS,8)]] x i8>) align 16 initializes((0, [[#div(VBITS,8)]])) %agg.result, ptr nocapture noundef readonly %0)
+// CHECK-SAME:   ptr dead_on_unwind noalias writable writeonly sret(<[[#div(VBITS,8)]] x i8>) align 16 captures(none) initializes((0, [[#div(VBITS,8)]])) %agg.result, ptr noundef readonly captures(none) %0)
 // CHECK-NEXT: entry:
 // CHECK-NEXT:   [[X:%.*]] = load <[[#div(VBITS,8)]] x i8>, ptr [[TMP0:%.*]], align 16, [[TBAA6:!tbaa !.*]]
 // CHECK-NEXT:   [[TMP1:%.*]] = tail call <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 31)

clang/test/CodeGen/PowerPC/aix-vaargs.c

@@ -68,8 +68,8 @@ void testva (int n, ...) {
 
 // CHECK: declare void @llvm.va_start.p0(ptr)
 
-// AIX32: declare void @llvm.memcpy.p0.p0.i32(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i32, i1 immarg)
-// AIX64: declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg)
+// AIX32: declare void @llvm.memcpy.p0.p0.i32(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i32, i1 immarg)
+// AIX64: declare void @llvm.memcpy.p0.p0.i64(ptr noalias writeonly captures(none), ptr noalias readonly captures(none), i64, i1 immarg)
 
 // CHECK: declare void @llvm.va_copy.p0(ptr, ptr)
 // CHECK: declare void @llvm.va_end.p0(ptr)

clang/test/CodeGen/SystemZ/systemz-inline-asm.c

@@ -123,7 +123,7 @@ double test_f64(double f, double g) {
 long double test_f128(long double f, long double g) {
   asm("axbr %0, %2" : "=f" (f) : "0" (f), "f" (g));
   return f;
-// CHECK: define{{.*}} void @test_f128(ptr dead_on_unwind noalias nocapture writable writeonly sret(fp128) align 8 initializes((0, 16)) [[DEST:%.*]], ptr nocapture noundef readonly %0, ptr nocapture noundef readonly %1)
+// CHECK: define{{.*}} void @test_f128(ptr dead_on_unwind noalias writable writeonly sret(fp128) align 8 captures(none) initializes((0, 16)) [[DEST:%.*]], ptr noundef readonly captures(none) %0, ptr noundef readonly captures(none) %1)
 // CHECK: %f = load fp128, ptr %0
 // CHECK: %g = load fp128, ptr %1
 // CHECK: [[RESULT:%.*]] = tail call fp128 asm "axbr $0, $2", "=f,0,f"(fp128 %f, fp128 %g)

clang/test/CodeGen/arm-cmse-attr.c

@@ -29,9 +29,9 @@ void f4(void) __attribute__((cmse_nonsecure_entry))
 {
 }
 
-// CHECK: define{{.*}} void @f1(ptr nocapture noundef readonly %fptr) {{[^#]*}}#0 {
+// CHECK: define{{.*}} void @f1(ptr noundef readonly captures(none) %fptr) {{[^#]*}}#0 {
 // CHECK: call void %fptr() #2
-// CHECK: define{{.*}} void @f2(ptr nocapture noundef readonly %fptr) {{[^#]*}}#0 {
+// CHECK: define{{.*}} void @f2(ptr noundef readonly captures(none) %fptr) {{[^#]*}}#0 {
 // CHECK: call void %fptr() #2
 // CHECK: define{{.*}} void @f3() {{[^#]*}}#1 {
 // CHECK: define{{.*}} void @f4() {{[^#]*}}#1 {

clang/test/CodeGen/arm-vfp16-arguments.c

@@ -71,6 +71,6 @@ void test_hfa(hfa_t a) {}
 
 hfa_t ghfa;
 hfa_t test_ret_hfa(void) { return ghfa; }
-// CHECK-SOFT: define{{.*}} void @test_ret_hfa(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.hfa_t) align 8 initializes((0, 16)) %agg.result)
+// CHECK-SOFT: define{{.*}} void @test_ret_hfa(ptr dead_on_unwind noalias writable writeonly sret(%struct.hfa_t) align 8 captures(none) initializes((0, 16)) %agg.result)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @test_ret_hfa()
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.hfa_t @test_ret_hfa()

clang/test/CodeGen/arm-vfp16-arguments2.cpp

@@ -37,27 +37,27 @@ struct S5 : B1 {
   B1 M[1];
 };
 
-// CHECK-SOFT: define{{.*}} void @_Z2f12S1(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.S1) align 8 initializes((0, 16)) %agg.result, [2 x i64] %s1.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f12S1(ptr dead_on_unwind noalias writable writeonly sret(%struct.S1) align 8 captures(none) initializes((0, 16)) %agg.result, [2 x i64] %s1.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f12S1([2 x <2 x i32>] returned %s1.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S1 @_Z2f12S1(%struct.S1 returned %s1.coerce)
 struct S1 f1(struct S1 s1) { return s1; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f22S2(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.S2) align 8 initializes((0, 16)) %agg.result, [4 x i32] %s2.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f22S2(ptr dead_on_unwind noalias writable writeonly sret(%struct.S2) align 8 captures(none) initializes((0, 16)) %agg.result, [4 x i32] %s2.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f22S2([2 x <2 x i32>] returned %s2.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S2 @_Z2f22S2(%struct.S2 %s2.coerce)
 struct S2 f2(struct S2 s2) { return s2; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f32S3(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.S3) align 8 initializes((0, 16)) %agg.result, [2 x i64] %s3.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f32S3(ptr dead_on_unwind noalias writable writeonly sret(%struct.S3) align 8 captures(none) initializes((0, 16)) %agg.result, [2 x i64] %s3.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f32S3([2 x <2 x i32>] returned %s3.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S3 @_Z2f32S3(%struct.S3 %s3.coerce)
 struct S3 f3(struct S3 s3) { return s3; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f42S4(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.S4) align 8 initializes((0, 16)) %agg.result, [2 x i64] %s4.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f42S4(ptr dead_on_unwind noalias writable writeonly sret(%struct.S4) align 8 captures(none) initializes((0, 16)) %agg.result, [2 x i64] %s4.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f42S4([2 x <2 x i32>] returned %s4.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S4 @_Z2f42S4(%struct.S4 %s4.coerce)
 struct S4 f4(struct S4 s4) { return s4; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f52S5(ptr dead_on_unwind noalias nocapture writable writeonly sret(%struct.S5) align 8 initializes((0, 16)) %agg.result, [2 x i64] %s5.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f52S5(ptr dead_on_unwind noalias writable writeonly sret(%struct.S5) align 8 captures(none) initializes((0, 16)) %agg.result, [2 x i64] %s5.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc %struct.S5 @_Z2f52S5(%struct.S5 %s5.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S5 @_Z2f52S5(%struct.S5 %s5.coerce)
 struct S5 f5(struct S5 s5) { return s5; }

clang/test/CodeGen/attr-counted-by-pr110385.c

@@ -26,7 +26,7 @@ struct bucket2 {
 void init(void * __attribute__((pass_dynamic_object_size(0))));
 
 // CHECK-LABEL: define dso_local void @test1(
-// CHECK-SAME: ptr nocapture noundef readonly [[FOO:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// CHECK-SAME: ptr noundef readonly captures(none) [[FOO:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
 // CHECK-NEXT:  entry:
 // CHECK-NEXT:    [[GROWABLE:%.*]] = getelementptr inbounds nuw i8, ptr [[FOO]], i64 8
 // CHECK-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[GROWABLE]], align 8, !tbaa [[TBAA2:![0-9]+]]