[PATCH] D40390: [InstCombine] Don't crash on out of bounds index in the insertelement

[Igor Laevsky via Phabricator via llvm-commits]

igor-laevsky updated this revision to Diff 125321.
igor-laevsky added a comment.

Updated with reduced test case


https://reviews.llvm.org/D40390

Files:
  lib/Transforms/InstCombine/InstCombineVectorOps.cpp
  test/Transforms/InstCombine/out-of-bounds-indexes.ll
  test/Transforms/InstCombine/vector_insertelt_shuffle.ll


Index: test/Transforms/InstCombine/vector_insertelt_shuffle.ll
===================================================================
--- test/Transforms/InstCombine/vector_insertelt_shuffle.ll
+++ test/Transforms/InstCombine/vector_insertelt_shuffle.ll
@@ -54,10 +54,10 @@
   ret <4 x float> %ins6
 }
 
+; Out of bounds index folds to undef
 define <4 x float> @bazzz(<4 x float> %x) {
 ; CHECK-LABEL: @bazzz(
-; CHECK-NEXT:    [[INS2:%.*]] = insertelement <4 x float> %x, float 2.000000e+00, i32 2
-; CHECK-NEXT:    ret <4 x float> [[INS2]]
+; CHECK-NEXT:   ret <4 x float> <float undef, float undef, float 2.000000e+00, float undef>
 ;
   %ins1 = insertelement<4 x float> %x, float 1.0, i32 5
   %ins2 = insertelement<4 x float> %ins1, float 2.0, i32 2
Index: test/Transforms/InstCombine/out-of-bounds-indexes.ll
===================================================================
--- test/Transforms/InstCombine/out-of-bounds-indexes.ll
+++ test/Transforms/InstCombine/out-of-bounds-indexes.ll
@@ -31,3 +31,11 @@
 }
 
 declare void @llvm.assume(i1)
+
+define <4 x double> @inselt_bad_index(<4 x double> %a) {
+; CHECK-LABEL: @inselt_bad_index(
+; CHECK-NEXT:    ret <4 x double> undef
+;
+  %I = insertelement <4 x double> %a, double 0.0, i64 4294967296
+  ret <4 x double> %I
+}
Index: lib/Transforms/InstCombine/InstCombineVectorOps.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineVectorOps.cpp
+++ lib/Transforms/InstCombine/InstCombineVectorOps.cpp
@@ -781,6 +781,10 @@
   Value *ScalarOp = IE.getOperand(1);
   Value *IdxOp    = IE.getOperand(2);
 
+  if (auto *V = SimplifyInsertElementInst(
+          VecOp, ScalarOp, IdxOp, SQ.getWithInstruction(&IE)))
+    return replaceInstUsesWith(IE, V);
+
   // Inserting an undef or into an undefined place, remove this.
   if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
     replaceInstUsesWith(IE, VecOp);


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