[llvm] r310639 - [InstCombine] Fix a crash in getSelectCondition if we happen to have two inverse vectors of i1 constants.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Thu Aug 10 10:48:14 2017
New Revision: 310639

URL: http://llvm.org/viewvc/llvm-project?rev=310639&view=rev
Log:
[InstCombine] Fix a crash in getSelectCondition if we happen to have two inverse vectors of i1 constants.

We used to try to truncate the constant vector to vXi1, but if it's already i1 this would fail. Instead we now use IRBuilder::getZExtOrTrunc which should check the type and only create a trunc if needed. I believe this should trigger constant folding in the IRBuilder and ultimately do the same thing just with the additional type check.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/or.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=310639&r1=310638&r2=310639&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Thu Aug 10 10:48:14 2017
@@ -1494,8 +1494,9 @@ static Value *getSelectCondition(Value *
   // If both operands are constants, see if the constants are inverse bitmasks.
   Constant *AC, *BC;
   if (match(A, m_Constant(AC)) && match(B, m_Constant(BC)) &&
-      areInverseVectorBitmasks(AC, BC))
-    return ConstantExpr::getTrunc(AC, CmpInst::makeCmpResultType(Ty));
+      areInverseVectorBitmasks(AC, BC)) {
+    return Builder.CreateZExtOrTrunc(AC, CmpInst::makeCmpResultType(Ty));
+  }
 
   // If both operands are xor'd with constants using the same sexted boolean
   // operand, see if the constants are inverse bitmasks.

Modified: llvm/trunk/test/Transforms/InstCombine/or.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/or.ll?rev=310639&r1=310638&r2=310639&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/or.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/or.ll Thu Aug 10 10:48:14 2017
@@ -828,3 +828,15 @@ define i1 @orn_and_cmp_4(i32 %a, i32 %b,
   %or = or i1 %and, %x_inv
   ret i1 %or
 }
+
+; The constant vectors are inverses. Make sure we can turn this into a select without crashing trying to truncate the constant to 16xi1.
+define <16 x i1> @test51(<16 x i1> %arg, <16 x i1> %arg1) {
+; CHECK-LABEL: @test51(
+; CHECK-NEXT:    [[TMP1:%.*]] = shufflevector <16 x i1> [[ARG:%.*]], <16 x i1> [[ARG1:%.*]], <16 x i32> <i32 0, i32 1, i32 2, i32 3, i32 20, i32 5, i32 6, i32 23, i32 24, i32 9, i32 10, i32 27, i32 28, i32 29, i32 30, i32 31>
+; CHECK-NEXT:    ret <16 x i1> [[TMP1]]
+;
+  %tmp = and <16 x i1> %arg, <i1 true, i1 true, i1 true, i1 true, i1 false, i1 true, i1 true, i1 false, i1 false, i1 true, i1 true, i1 false, i1 false, i1 false, i1 false, i1 false>
+  %tmp2 = and <16 x i1> %arg1, <i1 false, i1 false, i1 false, i1 false, i1 true, i1 false, i1 false, i1 true, i1 true, i1 false, i1 false, i1 true, i1 true, i1 true, i1 true, i1 true>
+  %tmp3 = or <16 x i1> %tmp, %tmp2
+  ret <16 x i1> %tmp3
+}