f946c70130
If left unchecked, the SLPVecrtorizer can move loads/stores below a stackrestore. The move can cause issues if the loads/stores have pointer operands from `alloca`s that are reset by the stackrestores. This patch adds the dependency check. The check is conservative, in that it does not check if the pointer operands of the loads/stores are actually from `alloca`s that may be reset. We did not observe any SPECCPU2017 performance degradation so this simple fix seems sufficient. The test could have been added to `llvm/test/Transforms/SLPVectorizer/X86/stacksave-dependence.ll`, but that test has not been updated to use opaque pointers. I am not inclined to add tests that still use typed pointers, or to refactor `llvm/test/Transforms/SLPVectorizer/X86/stacksave-dependence.ll` to use opaque pointers in this patch. If desired, I will open a different patch to refactor and consolidate the tests. Reviewed By: ABataev Differential Revision: https://reviews.llvm.org/D138585
42 lines
2.1 KiB
LLVM
42 lines
2.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -passes=slp-vectorizer -slp-threshold=-999 -mtriple=x86_64-unknown-linux-gnu -mcpu=skylake -S < %s | FileCheck %s
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; The test checks that loads should not be moved below a stackrestore boundary.
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define void @stackrestore1(ptr %out) {
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; CHECK-LABEL: @stackrestore1(
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; CHECK-NEXT: [[STACK:%.*]] = call ptr @llvm.stacksave()
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; CHECK-NEXT: [[LOCAL_ALLOCA:%.*]] = alloca [16 x i8], align 4
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; CHECK-NEXT: store <4 x float> <float 0x3FF3333340000000, float 0x3FF3333340000000, float 0x3FF3333340000000, float 0x3FF3333340000000>, ptr [[LOCAL_ALLOCA]], align 4
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; CHECK-NEXT: [[TMP1:%.*]] = load <4 x float>, ptr [[LOCAL_ALLOCA]], align 4
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; CHECK-NEXT: call void @llvm.stackrestore(ptr [[STACK]])
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; CHECK-NEXT: [[SHUFFLE:%.*]] = shufflevector <4 x float> [[TMP1]], <4 x float> poison, <4 x i32> <i32 2, i32 3, i32 0, i32 1>
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; CHECK-NEXT: store <4 x float> [[SHUFFLE]], ptr [[OUT:%.*]], align 4
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; CHECK-NEXT: ret void
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;
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%stack = call ptr @llvm.stacksave()
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%local_alloca = alloca [16 x i8], align 4
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store float 0x3FF3333340000000, ptr %local_alloca, align 4
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%addr1 = getelementptr inbounds i8, ptr %local_alloca, i64 4
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store float 0x3FF3333340000000, ptr %addr1, align 4
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%addr2 = getelementptr inbounds i8, ptr %local_alloca, i64 8
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store float 0x3FF3333340000000, ptr %addr2, align 4
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%addr3 = getelementptr inbounds i8, ptr %local_alloca, i64 12
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store float 0x3FF3333340000000, ptr %addr3, align 4
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%val0 = load float, ptr %local_alloca, align 4
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%val1 = load float, ptr %addr1, align 4
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%val2 = load float, ptr %addr2, align 4
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%val3 = load float, ptr %addr3, align 4
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call void @llvm.stackrestore(i8* %stack)
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%outaddr2 = getelementptr inbounds float, ptr %out, i64 2
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store float %val0, ptr %outaddr2, align 4
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%outaddr3 = getelementptr inbounds float, ptr %out, i64 3
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store float %val1, ptr %outaddr3, align 4
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store float %val2, ptr %out
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%outaddr1 = getelementptr inbounds float, ptr %out, i64 1
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store float %val3, ptr %outaddr1, align 4
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ret void
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}
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declare i8* @llvm.stacksave()
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declare void @llvm.stackrestore(i8*)
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