[PATCH] D51938: [InstCombine] Fix incorrect usage of getPrimitiveSizeInBits when we should be using the element size for vectors

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added a reviewer: spatel.

For vectors, getPrimitiveSizeInBits returns the full vector width. This code should using the element size for vectors. This could be fixed by calling getScalarSizeInBits, but its even easier to just get it from the APInt we're checking.


https://reviews.llvm.org/D51938

Files:
  lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
  test/Transforms/InstCombine/mul.ll


Index: test/Transforms/InstCombine/mul.ll
===================================================================
--- test/Transforms/InstCombine/mul.ll
+++ test/Transforms/InstCombine/mul.ll
@@ -409,7 +409,7 @@
 
 define <2 x i32> @test32vec(<2 x i32> %X) {
 ; CHECK-LABEL: @test32vec(
-; CHECK-NEXT:    [[MUL:%.*]] = shl nsw <2 x i32> [[X:%.*]], <i32 31, i32 31>
+; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X:%.*]], <i32 31, i32 31>
 ; CHECK-NEXT:    ret <2 x i32> [[MUL]]
 ;
   %mul = mul nsw <2 x i32> %X, <i32 -2147483648, i32 -2147483648>
Index: lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -171,14 +171,13 @@
     if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) {
       // Replace X*(2^C) with X << C, where C is either a scalar or a vector.
       if (Constant *NewCst = getLogBase2(NewOp->getType(), C1)) {
-        unsigned Width = NewCst->getType()->getPrimitiveSizeInBits();
         BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst);
 
         if (I.hasNoUnsignedWrap())
           Shl->setHasNoUnsignedWrap();
         if (I.hasNoSignedWrap()) {
           const APInt *V;
-          if (match(NewCst, m_APInt(V)) && *V != Width - 1)
+          if (match(NewCst, m_APInt(V)) && *V != V->getBitWidth() - 1)
             Shl->setHasNoSignedWrap();
         }
 


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