[llvm-commits] [llvm] r74646 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/bitcast-scalar-to-vector.ll

[Dan Gohman]

Author: djg
Date: Wed Jul  1 16:38:46 2009
New Revision: 74646

URL: http://llvm.org/viewvc/llvm-project?rev=74646&view=rev
Log:
Fix an instcombine abort on a scalar-to-vector bitcast. This fixes PR4487.

Added:
    llvm/trunk/test/Transforms/InstCombine/bitcast-scalar-to-vector.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=74646&r1=74645&r2=74646&view=diff

==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Wed Jul  1 16:38:46 2009
@@ -1085,8 +1085,22 @@
     break;
   }
   case Instruction::BitCast:
-    if (!I->getOperand(0)->getType()->isInteger())
+    if (!I->getOperand(0)->getType()->isIntOrIntVector())
       return false;  // vector->int or fp->int?
+
+    if (const VectorType *DstVTy = dyn_cast<VectorType>(I->getType())) {
+      if (const VectorType *SrcVTy =
+            dyn_cast<VectorType>(I->getOperand(0)->getType())) {
+        if (DstVTy->getNumElements() != SrcVTy->getNumElements())
+          // Don't touch a bitcast between vectors of different element counts.
+          return false;
+      } else
+        // Don't touch a scalar-to-vector bitcast.
+        return false;
+    } else if (isa<VectorType>(I->getOperand(0)->getType()))
+      // Don't touch a vector-to-scalar bitcast.
+      return false;
+
     if (SimplifyDemandedBits(I->getOperandUse(0), DemandedMask,
                              RHSKnownZero, RHSKnownOne, Depth+1))
       return I;

Added: llvm/trunk/test/Transforms/InstCombine/bitcast-scalar-to-vector.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/bitcast-scalar-to-vector.ll?rev=74646&view=auto

==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/bitcast-scalar-to-vector.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/bitcast-scalar-to-vector.ll Wed Jul  1 16:38:46 2009
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i32 0}
+; PR4487
+
+; Bitcasts between vectors and scalars are valid, despite being ill-advised.
+
+define i32 @test(i64 %a) {
+bb20:
+        %t1 = bitcast i64 %a to <2 x i32>
+        %t2 = bitcast i64 %a to <2 x i32>
+        %t3 = xor <2 x i32> %t1, %t2
+        %t4 = extractelement <2 x i32> %t3, i32 0
+        ret i32 %t4
+}
+