[llvm] 3890ce7 - [NFC][AggressiveInstCombine] Simplify code for shift truncation

[Anton Afanasyev via llvm-commits]

Author: Anton Afanasyev
Date: 2021-08-20T06:37:02+03:00
New Revision: 3890ce708d4f94d0326172650ce22262f6b56661

URL: https://github.com/llvm/llvm-project/commit/3890ce708d4f94d0326172650ce22262f6b56661
DIFF: https://github.com/llvm/llvm-project/commit/3890ce708d4f94d0326172650ce22262f6b56661.diff

LOG: [NFC][AggressiveInstCombine] Simplify code for shift truncation

Added: 
    

Modified: 
    llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
index ad4653ca5f1d8..c593e27aa4022 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
@@ -286,11 +286,10 @@ Type *TruncInstCombine::getBestTruncatedType() {
     if (I->getOpcode() == Instruction::Shl ||
         I->getOpcode() == Instruction::LShr) {
       KnownBits KnownRHS = computeKnownBits(I->getOperand(1), DL);
-      const unsigned SrcBitWidth = KnownRHS.getBitWidth();
       unsigned MinBitWidth = KnownRHS.getMaxValue()
-                                 .uadd_sat(APInt(SrcBitWidth, 1))
-                                 .getLimitedValue(SrcBitWidth);
-      if (MinBitWidth >= OrigBitWidth)
+                                 .uadd_sat(APInt(OrigBitWidth, 1))
+                                 .getLimitedValue(OrigBitWidth);
+      if (MinBitWidth == OrigBitWidth)
         return nullptr;
       if (I->getOpcode() == Instruction::LShr) {
         KnownBits KnownLHS = computeKnownBits(I->getOperand(0), DL);