[InstCombine] Propagate nsw flag when turning mul by pow2 into shift when the constant is a vector splat or the scalar bit width is larger than 64-bits

[craig.topper]

Summary

The check to see if we can propagate the nsw flag used m_ConstantInt(uint64_t*&) which doesn't work with splat vectors and has a restriction that the bitwidth of the ConstantInt must be 64-bits are less.

This patch changes it to use m_APInt to remove both these issues.

[spatel]

LGTM.

llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) {
 
       if (NewCst) {
         unsigned Width = NewCst->getType()->getPrimitiveSizeInBits();
         BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst);
 
         if (I.hasNoUnsignedWrap())
           Shl->setHasNoUnsignedWrap();
         if (I.hasNoSignedWrap()) {
-          uint64_t V;
-          if (match(NewCst, m_ConstantInt(V)) && V != Width - 1)
+          const APInt *V;
+          if (match(NewCst, m_APInt(V)) && *V != Width - 1)
             Shl->setHasNoSignedWrap();
         }
 
         return Shl;
       }
     }
   }
 

llvm/trunk/test/Transforms/InstCombine/mul.ll

; CHECK-LABEL: @test32
   %mul = mul nsw i32 %X, -2147483648
   ret i32 %mul
 ; CHECK:      %[[shl:.*]] = shl i32 %X, 31
 ; CHECK-NEXT: ret i32 %[[shl]]
 }
 
 define <2 x i32> @test32vec(<2 x i32> %X) {
 ; CHECK-LABEL: @test32vec(
-; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X:%.*]], <i32 31, i32 31>
+; CHECK-NEXT:    [[MUL:%.*]] = shl nsw <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>
   ret <2 x i32> %mul
 }
 
 define i32 @test33(i32 %X) {
 ; CHECK-LABEL: @test33
   %mul = mul nsw i32 %X, 1073741824
 ; CHECK:      %[[shl:.*]] = shl nsw i32 %X, 30
 ; CHECK-NEXT: ret i32 %[[shl]]
   ret i32 %mul
 }
 
-; TODO: we should propagate nsw flag to the shift here
 define <2 x i32> @test33vec(<2 x i32> %X) {
 ; CHECK-LABEL: @test33vec(
-; CHECK-NEXT:    [[MUL:%.*]] = shl <2 x i32> [[X:%.*]], <i32 30, i32 30>
+; CHECK-NEXT:    [[MUL:%.*]] = shl nsw <2 x i32> [[X:%.*]], <i32 30, i32 30>
 ; CHECK-NEXT:    ret <2 x i32> [[MUL]]
 ;
   %mul = mul nsw <2 x i32> %X, <i32 1073741824, i32 1073741824>
   ret <2 x i32> %mul
 }
 
-; TODO: we should propagate nsw flag to the shift here, but we only handle i64 and smaller
 define i128 @test34(i128 %X) {
 ; CHECK-LABEL: @test34(
-; CHECK-NEXT:    [[MUL:%.*]] = shl i128 [[X:%.*]], 1
+; CHECK-NEXT:    [[MUL:%.*]] = shl nsw i128 [[X:%.*]], 1
 ; CHECK-NEXT:    ret i128 [[MUL]]
 ;
   %mul = mul nsw i128 %X, 2
   ret i128 %mul
 }