[llvm-branch-commits] [llvm] 2eb558c - [SLP] Check for PHI nodes (potentially cycles!) when checking dependencies
Tom Stellard via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri Feb 14 14:32:55 PST 2025
Author: Alexey Bataev
Date: 2025-02-14T14:32:31-08:00
New Revision: 2eb558c99d967af093340def231c9a1ba228571b
URL: https://github.com/llvm/llvm-project/commit/2eb558c99d967af093340def231c9a1ba228571b
DIFF: https://github.com/llvm/llvm-project/commit/2eb558c99d967af093340def231c9a1ba228571b.diff
LOG: [SLP] Check for PHI nodes (potentially cycles!) when checking dependencies
When checking for dependecies for gather nodes with users with the same
last instruction, cannot rely on the index order, if there is (even
potential!) cycle in the graph, which may cause order not work correctly
and cause compiler crash.
Fixes #127128
(cherry picked from commit ac217ee389d63124432e5e6890851a678f7a676b)
Added:
llvm/test/Transforms/SLPVectorizer/X86/phi-node-with-cycle.ll
Modified:
llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll
llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 19963e780ebd3..7b20eda550095 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -13181,8 +13181,16 @@ BoUpSLP::isGatherShuffledSingleRegisterEntry(
continue;
// If the user instruction is used for some reason in
diff erent
// vectorized nodes - make it depend on index.
+ // If any vector node is PHI node, this dependency might not work
+ // because of cycle dependencies, so disable it.
if (TEUseEI.UserTE != UseEI.UserTE &&
- TEUseEI.UserTE->Idx < UseEI.UserTE->Idx)
+ (TEUseEI.UserTE->Idx < UseEI.UserTE->Idx ||
+ any_of(
+ VectorizableTree,
+ [](const std::unique_ptr<TreeEntry> &TE) {
+ return TE->State == TreeEntry::Vectorize &&
+ TE->getOpcode() == Instruction::PHI;
+ })))
continue;
}
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll b/llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll
index 5562291dbb6be..bf3f0c4df74e4 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll
@@ -31,7 +31,7 @@ define void @test() {
; CHECK-NEXT: [[TOBOOL:%.*]] = fcmp une float [[I2]], 0.000000e+00
; CHECK-NEXT: [[TMP8:%.*]] = shufflevector <2 x float> [[TMP5]], <2 x float> poison, <2 x i32> <i32 poison, i32 0>
; CHECK-NEXT: [[TMP9]] = insertelement <2 x float> [[TMP8]], float [[I2]], i32 0
-; CHECK-NEXT: [[TMP10]] = shufflevector <2 x float> [[TMP9]], <2 x float> [[TMP2]], <2 x i32> <i32 0, i32 3>
+; CHECK-NEXT: [[TMP10]] = insertelement <2 x float> [[TMP2]], float [[I2]], i32 0
; CHECK-NEXT: br i1 [[TOBOOL]], label [[BB1]], label [[BB2]]
;
entry:
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll b/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
index 166c819098c8c..d649465c9ff12 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
@@ -8,7 +8,7 @@
; YAML: Function: test
; YAML: Args:
; YAML: - String: 'Stores SLP vectorized with cost '
-; YAML: - Cost: '-6'
+; YAML: - Cost: '-3'
; YAML: - String: ' and with tree size '
; YAML: - TreeSize: '14'
; YAML: ...
diff --git a/llvm/test/Transforms/SLPVectorizer/X86/phi-node-with-cycle.ll b/llvm/test/Transforms/SLPVectorizer/X86/phi-node-with-cycle.ll
new file mode 100644
index 0000000000000..22e7e6a8e6624
--- /dev/null
+++ b/llvm/test/Transforms/SLPVectorizer/X86/phi-node-with-cycle.ll
@@ -0,0 +1,59 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S --passes=slp-vectorizer -mtriple=x86_64-unknown-linux-gnu -mcpu=haswell < %s | FileCheck %s
+
+define void @test(float %0) {
+; CHECK-LABEL: define void @test(
+; CHECK-SAME: float [[TMP0:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: [[TMP2:%.*]] = insertelement <2 x float> <float 0.000000e+00, float poison>, float [[TMP0]], i32 1
+; CHECK-NEXT: [[TMP3:%.*]] = fdiv <2 x float> [[TMP2]], zeroinitializer
+; CHECK-NEXT: [[TMP4:%.*]] = insertelement <2 x float> <float poison, float 0.000000e+00>, float [[TMP0]], i32 0
+; CHECK-NEXT: [[TMP5:%.*]] = fdiv <2 x float> [[TMP4]], zeroinitializer
+; CHECK-NEXT: br label %[[BB6:.*]]
+; CHECK: [[BB6]]:
+; CHECK-NEXT: [[TMP7:%.*]] = fmul <2 x float> [[TMP5]], zeroinitializer
+; CHECK-NEXT: [[TMP8:%.*]] = fsub <2 x float> zeroinitializer, [[TMP7]]
+; CHECK-NEXT: br label %[[BB10:.*]]
+; CHECK: [[BB9:.*]]:
+; CHECK-NEXT: br label %[[BB10]]
+; CHECK: [[BB10]]:
+; CHECK-NEXT: [[TMP11:%.*]] = phi <2 x float> [ [[TMP8]], %[[BB6]] ], [ poison, %[[BB9]] ]
+; CHECK-NEXT: br label %[[BB12:.*]]
+; CHECK: [[BB12]]:
+; CHECK-NEXT: [[TMP13:%.*]] = fmul <2 x float> [[TMP3]], zeroinitializer
+; CHECK-NEXT: [[TMP14:%.*]] = fsub <2 x float> [[TMP11]], [[TMP13]]
+; CHECK-NEXT: [[TMP15:%.*]] = extractelement <2 x float> [[TMP14]], i32 0
+; CHECK-NEXT: [[TMP16:%.*]] = extractelement <2 x float> [[TMP14]], i32 1
+; CHECK-NEXT: [[TMP17:%.*]] = fadd float [[TMP15]], [[TMP16]]
+; CHECK-NEXT: [[TMP18:%.*]] = call float @llvm.fabs.f32(float [[TMP17]])
+; CHECK-NEXT: ret void
+;
+ %2 = fdiv float 0.000000e+00, 0.000000e+00
+ %3 = fdiv float 0.000000e+00, 0.000000e+00
+ %4 = fdiv float %0, 0.000000e+00
+ br label %5
+
+5:
+ %6 = fmul float %4, 0.000000e+00
+ %7 = fsub float 0.000000e+00, %6
+ %8 = fmul float %3, 0.000000e+00
+ %9 = fsub float 0.000000e+00, %8
+ br label %11
+
+10:
+ br label %11
+
+11:
+ %12 = phi float [ %7, %5 ], [ 0.000000e+00, %10 ]
+ %13 = phi float [ %9, %5 ], [ 0.000000e+00, %10 ]
+ br label %14
+
+14:
+ %15 = fmul float %2, 0.000000e+00
+ %16 = fsub float %12, %15
+ %17 = fmul float %4, 0.000000e+00
+ %18 = fsub float %13, %17
+ %19 = fadd float %16, %18
+ %20 = call float @llvm.fabs.f32(float %19)
+ ret void
+}
+
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