Added missing LLVM_EXTERNAL_VISIBILITY #32
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closed due to closing #31 |
espressif-bot
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Jul 1, 2025
Combine sequences such as:
```llvm
%pn1 = phi [init1, %BB1], [%op1, %BB2]
%pn2 = phi [init2, %BB1], [%op2, %BB2]
%op1 = binop %pn1, constant1
%op2 = binop %pn2, constant2
%rdx = binop %op1, %op2
```
Into:
```llvm
%phi_combined = phi [init_combined, %BB1], [%op_combined, %BB2]
%rdx_combined = binop %phi_combined, constant_combined
```
This allows us to simplify interleaved reductions, for example as
introduced by the loop vectorizer.
The anecdotal example for this is the loop below:
```c
float foo() {
float q = 1.f;
for (int i = 0; i < 1000; ++i)
q *= .99f;
return q;
}
```
Which currently gets lowered explicitly such as (on AArch64,
interleaved by four):
```gas
.LBB0_1:
fmul v0.4s, v0.4s, v1.4s
fmul v2.4s, v2.4s, v1.4s
fmul v3.4s, v3.4s, v1.4s
fmul v4.4s, v4.4s, v1.4s
subs w8, w8, #32
b.ne .LBB0_1
```
But with this patch lowers trivially:
```gas
foo:
mov w8, llvm#5028
movk w8, llvm#14389, lsl #16
fmov s0, w8
ret
```
espressif-bot
pushed a commit
that referenced
this pull request
Aug 7, 2025
…lvm#152156) With this new A320 in-order core, we follow adding the FeatureUseFixedOverScalableIfEqualCost feature to A510 and A520 (llvm#132246), which reaps the same code generation benefits of preferring fixed over scalable when the cost is equal. So when we have: ``` void foo(float* a, float* b, float* dst, unsigned n) { for (unsigned i = 0; i < n; ++i) dst[i] = a[i] + b[i]; } ``` When compiling without the feature enabled, we get: ``` ... ld1b { z0.b }, p0/z, [x0, x10] ld1b { z2.b }, p0/z, [x1, x10] add x12, x0, x10 ldr z1, [x12, #1, mul vl] add x12, x1, x10 ldr z3, [x12, #1, mul vl] fadd z0.s, z2.s, z0.s add x12, x2, x10 fadd z1.s, z3.s, z1.s dech x11 st1b { z0.b }, p0, [x2, x10] incb x10, all, mul #2 str z1, [x12, #1, mul vl] ... ``` When compiling with, we get: ``` ... ldp q0, q1, [x12, #-16] ldp q2, q3, [x11, #-16] subs x13, x13, #8 fadd v0.4s, v2.4s, v0.4s fadd v1.4s, v3.4s, v1.4s add x11, x11, #32 add x12, x12, #32 stp q0, q1, [x10, #-16] add x10, x10, #32 ... ```
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Quick fix for #31