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Merged
merged 1 commit into from
Feb 25, 2025
Merged

release/20.x: [SLP] Check for PHI nodes (potentially cycles!) when checking dependencies: Backport Attempt 3 #128371

merged 1 commit into from
Feb 25, 2025

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@Zentrik
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@Zentrik Zentrik commented Feb 22, 2025

Backport ac217ee

This fixes #127294 by updating the test at llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll

@Zentrik Zentrik changed the title release/20.x: [SLP] Check for PHI nodes (potentially cycles!) when checking dependencies release/20.x: [SLP] Check for PHI nodes (potentially cycles!) when checking dependencies: Backport Attempt 3 Feb 22, 2025
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llvmbot commented Feb 22, 2025

@llvm/pr-subscribers-vectorizers

Author: None (Zentrik)

Changes

Backport ac217ee

This fixes #127294 by updating the test at llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll

Full diff: https://github.com/llvm/llvm-project/pull/128371.diff

5 Files Affected:

  • (modified) llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp (+9-1)
  • (modified) llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll (+1-1)
  • (modified) llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll (+1-1)
  • (modified) llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll (+7-6)
  • (added) llvm/test/Transforms/SLPVectorizer/X86/phi-node-with-cycle.ll (+59)
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 different
         // 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/perfect-matched-reused-bv.ll b/llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll
index 1053e0fc10669..c4a49242a5583 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll
@@ -7,16 +7,17 @@ define void @test() {
 ; CHECK-NEXT:  [[BB:.*]]:
 ; CHECK-NEXT:    br label %[[BB1:.*]]
 ; CHECK:       [[BB1]]:
-; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ zeroinitializer, %[[BB]] ], [ [[TMP4:%.*]], %[[BB4:.*]] ]
-; CHECK-NEXT:    [[TMP1:%.*]] = or <2 x i32> [[TMP0]], zeroinitializer
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ 0, %[[BB]] ], [ [[ADD6:%.*]], %[[BB4:.*]] ]
+; CHECK-NEXT:    [[PHI2:%.*]] = phi i32 [ 0, %[[BB]] ], [ 0, %[[BB4]] ]
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[PHI2]], 0
+; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[PHI]], 0
 ; CHECK-NEXT:    br i1 false, label %[[BB7:.*]], label %[[BB4]]
 ; CHECK:       [[BB4]]:
-; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <2 x i32> [[TMP0]], <2 x i32> <i32 0, i32 poison>, <2 x i32> <i32 2, i32 1>
-; CHECK-NEXT:    [[TMP3:%.*]] = add <2 x i32> zeroinitializer, [[TMP2]]
-; CHECK-NEXT:    [[TMP4]] = add <2 x i32> zeroinitializer, [[TMP2]]
+; CHECK-NEXT:    [[ADD6]] = add i32 [[PHI]], 0
 ; CHECK-NEXT:    br i1 false, label %[[BB7]], label %[[BB1]]
 ; CHECK:       [[BB7]]:
-; CHECK-NEXT:    [[TMP5:%.*]] = phi <2 x i32> [ [[TMP1]], %[[BB1]] ], [ [[TMP3]], %[[BB4]] ]
+; CHECK-NEXT:    [[PHI8:%.*]] = phi i32 [ [[OR]], %[[BB1]] ], [ 0, %[[BB4]] ]
+; CHECK-NEXT:    [[PHI9:%.*]] = phi i32 [ [[OR3]], %[[BB1]] ], [ [[ADD6]], %[[BB4]] ]
 ; CHECK-NEXT:    ret void
 ;
 bb:
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
+}
+

@llvmbot
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llvmbot commented Feb 22, 2025

@llvm/pr-subscribers-llvm-transforms

Author: None (Zentrik)

Changes

Backport ac217ee

This fixes #127294 by updating the test at llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll

Full diff: https://github.com/llvm/llvm-project/pull/128371.diff

5 Files Affected:

  • (modified) llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp (+9-1)
  • (modified) llvm/test/Transforms/SLPVectorizer/X86/delayed-gather-emission.ll (+1-1)
  • (modified) llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll (+1-1)
  • (modified) llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll (+7-6)
  • (added) llvm/test/Transforms/SLPVectorizer/X86/phi-node-with-cycle.ll (+59)
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 different
         // 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/perfect-matched-reused-bv.ll b/llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll
index 1053e0fc10669..c4a49242a5583 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/perfect-matched-reused-bv.ll
@@ -7,16 +7,17 @@ define void @test() {
 ; CHECK-NEXT:  [[BB:.*]]:
 ; CHECK-NEXT:    br label %[[BB1:.*]]
 ; CHECK:       [[BB1]]:
-; CHECK-NEXT:    [[TMP0:%.*]] = phi <2 x i32> [ zeroinitializer, %[[BB]] ], [ [[TMP4:%.*]], %[[BB4:.*]] ]
-; CHECK-NEXT:    [[TMP1:%.*]] = or <2 x i32> [[TMP0]], zeroinitializer
+; CHECK-NEXT:    [[PHI:%.*]] = phi i32 [ 0, %[[BB]] ], [ [[ADD6:%.*]], %[[BB4:.*]] ]
+; CHECK-NEXT:    [[PHI2:%.*]] = phi i32 [ 0, %[[BB]] ], [ 0, %[[BB4]] ]
+; CHECK-NEXT:    [[OR:%.*]] = or i32 [[PHI2]], 0
+; CHECK-NEXT:    [[OR3:%.*]] = or i32 [[PHI]], 0
 ; CHECK-NEXT:    br i1 false, label %[[BB7:.*]], label %[[BB4]]
 ; CHECK:       [[BB4]]:
-; CHECK-NEXT:    [[TMP2:%.*]] = shufflevector <2 x i32> [[TMP0]], <2 x i32> <i32 0, i32 poison>, <2 x i32> <i32 2, i32 1>
-; CHECK-NEXT:    [[TMP3:%.*]] = add <2 x i32> zeroinitializer, [[TMP2]]
-; CHECK-NEXT:    [[TMP4]] = add <2 x i32> zeroinitializer, [[TMP2]]
+; CHECK-NEXT:    [[ADD6]] = add i32 [[PHI]], 0
 ; CHECK-NEXT:    br i1 false, label %[[BB7]], label %[[BB1]]
 ; CHECK:       [[BB7]]:
-; CHECK-NEXT:    [[TMP5:%.*]] = phi <2 x i32> [ [[TMP1]], %[[BB1]] ], [ [[TMP3]], %[[BB4]] ]
+; CHECK-NEXT:    [[PHI8:%.*]] = phi i32 [ [[OR]], %[[BB1]] ], [ 0, %[[BB4]] ]
+; CHECK-NEXT:    [[PHI9:%.*]] = phi i32 [ [[OR3]], %[[BB1]] ], [ [[ADD6]], %[[BB4]] ]
 ; CHECK-NEXT:    ret void
 ;
 bb:
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
+}
+

@Zentrik
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Zentrik commented Feb 22, 2025

I suspect I don't have permissions to add this to the milestone.

@Zentrik Zentrik mentioned this pull request Feb 22, 2025
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@nikic nikic added this to the LLVM 20.X Release milestone Feb 22, 2025
@nikic nikic mentioned this pull request Feb 22, 2025
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@nikic nikic requested a review from alexey-bataev February 22, 2025 22:02
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LG

@alexey-bataev @tstellar
[SLP] Check for PHI nodes (potentially cycles!) when checking depende…
098492a 
…ncies

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 llvm#127128

(cherry picked from commit ac217ee)
@tstellar tstellar merged commit 098492a into llvm:release/20.x Feb 25, 2025
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@Zentrik (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.

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