[llvm] r332055 - [InstCombine] Replace an 'if' that should always be true with an assert.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Thu May 10 15:45:28 2018
New Revision: 332055

URL: http://llvm.org/viewvc/llvm-project?rev=332055&view=rev
Log:
[InstCombine] Replace an 'if' that should always be true with an assert.

The bitwidth of the operation should always be wider than the result width of the truncate since we don't recurse through any width changing operations.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=332055&r1=332054&r2=332055&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Thu May 10 15:45:28 2018
@@ -364,13 +364,12 @@ static bool canEvaluateTruncated(Value *
     // UDiv and URem can be truncated if all the truncated bits are zero.
     uint32_t OrigBitWidth = OrigTy->getScalarSizeInBits();
     uint32_t BitWidth = Ty->getScalarSizeInBits();
-    if (BitWidth < OrigBitWidth) {
-      APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
-      if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) &&
-          IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) {
-        return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
-               canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
-      }
+    assert(BitWidth < OrigBitWidth && "Unexpected bitwidths!");
+    APInt Mask = APInt::getBitsSetFrom(OrigBitWidth, BitWidth);
+    if (IC.MaskedValueIsZero(I->getOperand(0), Mask, 0, CxtI) &&
+        IC.MaskedValueIsZero(I->getOperand(1), Mask, 0, CxtI)) {
+      return canEvaluateTruncated(I->getOperand(0), Ty, IC, CxtI) &&
+             canEvaluateTruncated(I->getOperand(1), Ty, IC, CxtI);
     }
     break;
   }