[llvm] [InterleavedAccessPass] Avoid optimizing load instructions if it has dead binop users (PR #71339)
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Sun Nov 5 15:28:14 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: None (Skwoogey)
<details>
<summary>Changes</summary>
If a load instruction qualifies to be optimized by InterleavedAccess Pass, but also has a dead binop instruction this will lead to a crash.
Binop instruction will not be deleted, because normally it would be deleted through its' users, but it has none. Later on deleting a load instruction will fail because it still has uses.
---
Full diff: https://github.com/llvm/llvm-project/pull/71339.diff
2 Files Affected:
- (modified) llvm/lib/CodeGen/InterleavedAccessPass.cpp (+1-1)
- (modified) llvm/test/Transforms/InterleavedAccess/AArch64/binopshuffles.ll (+21)
``````````diff
diff --git a/llvm/lib/CodeGen/InterleavedAccessPass.cpp b/llvm/lib/CodeGen/InterleavedAccessPass.cpp
index 6b3848531569c0b..672caea3086cd63 100644
--- a/llvm/lib/CodeGen/InterleavedAccessPass.cpp
+++ b/llvm/lib/CodeGen/InterleavedAccessPass.cpp
@@ -251,7 +251,7 @@ bool InterleavedAccess::lowerInterleavedLoad(
continue;
}
if (auto *BI = dyn_cast<BinaryOperator>(User)) {
- if (all_of(BI->users(), [](auto *U) {
+ if (!BI->users().empty() && all_of(BI->users(), [](auto *U) {
auto *SVI = dyn_cast<ShuffleVectorInst>(U);
return SVI && isa<UndefValue>(SVI->getOperand(1));
})) {
diff --git a/llvm/test/Transforms/InterleavedAccess/AArch64/binopshuffles.ll b/llvm/test/Transforms/InterleavedAccess/AArch64/binopshuffles.ll
index 67910305f56d66c..2e8a7cf42ac506b 100644
--- a/llvm/test/Transforms/InterleavedAccess/AArch64/binopshuffles.ll
+++ b/llvm/test/Transforms/InterleavedAccess/AArch64/binopshuffles.ll
@@ -220,3 +220,24 @@ entry:
store <8 x i8> %shuffled, ptr %p2
ret void
}
+
+define void @skip_optimizing_dead_binop(ptr %p0, ptr %p1) {
+; CHECK-LABEL: @skip_optimizing_dead_binop(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[V0:%.*]] = load <8 x double>, ptr [[P0:%.*]]
+; CHECK-NEXT: [[SHUFFLED_1:%.*]] = shufflevector <8 x double> [[V0]], <8 x double> undef, <2 x i32> <i32 0, i32 4>
+; CHECK-NEXT: [[SHUFFLED_2:%.*]] = shufflevector <8 x double> [[V0]], <8 x double> undef, <2 x i32> <i32 1, i32 5>
+; CHECK-NEXT: [[SHUFFLED_3:%.*]] = shufflevector <8 x double> [[V0]], <8 x double> undef, <2 x i32> <i32 2, i32 6>
+; CHECK-NEXT: [[SHUFFLED_4:%.*]] = shufflevector <8 x double> [[V0]], <8 x double> undef, <2 x i32> <i32 3, i32 7>
+; CHECK-NEXT: [[DEAD_BINOP:%.*]] = fadd <8 x double> [[V0]], [[V0]]
+; CHECK-NEXT: ret void
+;
+entry:
+ %v0 = load <8 x double>, ptr %p0
+ %shuffled_1 = shufflevector <8 x double> %v0, <8 x double> undef, <2 x i32> <i32 0, i32 4>
+ %shuffled_2 = shufflevector <8 x double> %v0, <8 x double> undef, <2 x i32> <i32 1, i32 5>
+ %shuffled_3 = shufflevector <8 x double> %v0, <8 x double> undef, <2 x i32> <i32 2, i32 6>
+ %shuffled_4 = shufflevector <8 x double> %v0, <8 x double> undef, <2 x i32> <i32 3, i32 7>
+ %dead_binop = fadd <8 x double> %v0, %v0
+ ret void
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/71339
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