[PATCH] D107058: [SLP]Fix a crash in gathered loads analysis.

[Alexey Bataev via Phabricator via llvm-commits]

ABataev created this revision.
ABataev added reviewers: RKSimon, spatel, anton-afanasyev, dtemirbulatov, sdesmalen.
Herald added a subscriber: hiraditya.
ABataev requested review of this revision.
Herald added a project: LLVM.

Need to check that the minimum acceptable vector factor is at least 2,
not 0, to avoid compiler crash during gathered loads analysis.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107058

Files:
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
  llvm/test/Transforms/SLPVectorizer/AArch64/loads-gather-crash.ll


Index: llvm/test/Transforms/SLPVectorizer/AArch64/loads-gather-crash.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SLPVectorizer/AArch64/loads-gather-crash.ll
@@ -0,0 +1,32 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -slp-vectorizer -mtriple=aarch64-unknown-linux-gnu < %s | FileCheck %s
+
+define void @foo() local_unnamed_addr {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = load volatile double, double* poison, align 8
+; CHECK-NEXT:    [[TMP1:%.*]] = load volatile double, double* poison, align 8
+; CHECK-NEXT:    [[TMP2:%.*]] = load volatile double, double* poison, align 8
+; CHECK-NEXT:    [[TMP3:%.*]] = load volatile double, double* poison, align 8
+; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[D30_0734:%.*]] = phi double [ undef, [[FOR_BODY]] ], [ [[TMP0]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[D01_0733:%.*]] = phi double [ undef, [[FOR_BODY]] ], [ [[TMP1]], [[ENTRY]] ]
+; CHECK-NEXT:    [[D11_0732:%.*]] = phi double [ undef, [[FOR_BODY]] ], [ [[TMP2]], [[ENTRY]] ]
+; CHECK-NEXT:    [[D21_0731:%.*]] = phi double [ undef, [[FOR_BODY]] ], [ [[TMP3]], [[ENTRY]] ]
+; CHECK-NEXT:    br label [[FOR_BODY]]
+;
+entry:
+  %0 = load volatile double, double* poison, align 8
+  %1 = load volatile double, double* poison, align 8
+  %2 = load volatile double, double* poison, align 8
+  %3 = load volatile double, double* poison, align 8
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %d30.0734 = phi double [ undef, %for.body ], [ %0, %entry ]
+  %d01.0733 = phi double [ undef, %for.body ], [ %1, %entry ]
+  %d11.0732 = phi double [ undef, %for.body ], [ %2, %entry ]
+  %d21.0731 = phi double [ undef, %for.body ], [ %3, %entry ]
+  br label %for.body
+}
Index: llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4187,8 +4187,8 @@
       unsigned VectorizedCnt = 0;
       unsigned ScatterVectorizeCnt = 0;
       const unsigned Sz = DL->getTypeSizeInBits(E->getMainOp()->getType());
-      for (unsigned MinVF = getMinVecRegSize() / (2 * Sz); VF >= MinVF;
-           VF /= 2) {
+      for (unsigned MinVF = std::max(2U, getMinVecRegSize() / (2 * Sz));
+           VF >= MinVF; VF /= 2) {
         for (unsigned Cnt = StartIdx, End = VL.size(); Cnt + VF <= End;
              Cnt += VF) {
           ArrayRef<Value *> Slice = VL.slice(Cnt, VF);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D107058.362724.patch
Type: text/x-patch
Size: 2678 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20210729/c22538f5/attachment.bin>