Back-port r276209:

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r276209 | spatel | 2016-07-20 16:40:01 -0700 (Wed, 20 Jul 2016) | 4 lines

[InstSimplify][InstCombine] don't crash when folding vector selects of icmp

Differential Revision: https://reviews.llvm.org/D22602

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_39@276986 91177308-0d34-0410-b5e6-96231b3b80d8

Author: zmodem

lib/Analysis/InstructionSimplify.cpp

@@ -3400,7 +3400,10 @@ static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
     return TrueVal;
 
   if (const auto *ICI = dyn_cast<ICmpInst>(CondVal)) {
-    unsigned BitWidth = Q.DL.getTypeSizeInBits(TrueVal->getType());
+    // FIXME: This code is nearly duplicated in InstCombine. Using/refactoring
+    // decomposeBitTestICmp() might help.
+    unsigned BitWidth =
+        Q.DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
     ICmpInst::Predicate Pred = ICI->getPredicate();
     Value *CmpLHS = ICI->getOperand(0);
     Value *CmpRHS = ICI->getOperand(1);

lib/Transforms/InstCombine/InstCombineSelect.cpp

@@ -553,8 +553,11 @@ Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
     }
   }
 
+  // FIXME: This code is nearly duplicated in InstSimplify. Using/refactoring
+  // decomposeBitTestICmp() might help.
   {
-    unsigned BitWidth = DL.getTypeSizeInBits(TrueVal->getType());
+    unsigned BitWidth =
+        DL.getTypeSizeInBits(TrueVal->getType()->getScalarType());
     APInt MinSignedValue = APInt::getSignBit(BitWidth);
     Value *X;
     const APInt *Y, *C;

test/Transforms/InstCombine/select.ll

@@ -1737,3 +1737,26 @@ define i32 @PR27137(i32 %a) {
   %s1 = select i1 %c1, i32 %s0, i32 -1
   ret i32 %s1
 }
+
+define i32 @select_icmp_slt0_xor(i32 %x) {
+; CHECK-LABEL: @select_icmp_slt0_xor(
+; CHECK-NEXT:    [[TMP1:%.*]] = or i32 %x, -2147483648
+; CHECK-NEXT:    ret i32 [[TMP1]]
+;
+  %cmp = icmp slt i32 %x, zeroinitializer
+  %xor = xor i32 %x, 2147483648
+  %x.xor = select i1 %cmp, i32 %x, i32 %xor
+  ret i32 %x.xor
+}
+
+define <2 x i32> @select_icmp_slt0_xor_vec(<2 x i32> %x) {
+; CHECK-LABEL: @select_icmp_slt0_xor_vec(
+; CHECK-NEXT:    [[TMP1:%.*]] = or <2 x i32> %x, <i32 -2147483648, i32 -2147483648>
+; CHECK-NEXT:    ret <2 x i32> [[TMP1]]
+;
+  %cmp = icmp slt <2 x i32> %x, zeroinitializer
+  %xor = xor <2 x i32> %x, <i32 2147483648, i32 2147483648>
+  %x.xor = select <2 x i1> %cmp, <2 x i32> %x, <2 x i32> %xor
+  ret <2 x i32> %x.xor
+}
+