[InstCombine] Use disjoint flag in mul of or fold

Slightly more powerful if the information used to infer disjoint
was lost.

Author: nikic

llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

@@ -300,9 +300,8 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
     // Canonicalize (X|C1)*MulC -> X*MulC+C1*MulC.
     Value *X;
     Constant *C1;
-    if ((match(Op0, m_OneUse(m_Add(m_Value(X), m_ImmConstant(C1))))) ||
-        (match(Op0, m_OneUse(m_Or(m_Value(X), m_ImmConstant(C1)))) &&
-         haveNoCommonBitsSet(X, C1, SQ.getWithInstruction(&I)))) {
+    if (match(Op0, m_OneUse(m_Add(m_Value(X), m_ImmConstant(C1)))) ||
+        match(Op0, m_OneUse(m_DisjointOr(m_Value(X), m_ImmConstant(C1))))) {
       // C1*MulC simplifies to a tidier constant.
       Value *NewC = Builder.CreateMul(C1, MulC);
       auto *BOp0 = cast<BinaryOperator>(Op0);

llvm/test/Transforms/InstCombine/mul.ll

@@ -964,6 +964,28 @@ define i32 @PR57278_mul_assume(i32 %a) {
 
 declare void @llvm.assume(i1)
 
+define i32 @PR57278_or_disjoint_nuw(i32 %a) {
+; CHECK-LABEL: @PR57278_or_disjoint_nuw(
+; CHECK-NEXT:    [[TMP1:%.*]] = mul nuw i32 [[A:%.*]], 3
+; CHECK-NEXT:    [[MUL:%.*]] = add nuw i32 [[TMP1]], 9
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %add = or disjoint i32 %a, 3
+  %mul = mul nuw i32 %add, 3
+  ret i32 %mul
+}
+
+define i32 @PR57278_or_disjoint_nsw(i32 %a) {
+; CHECK-LABEL: @PR57278_or_disjoint_nsw(
+; CHECK-NEXT:    [[TMP1:%.*]] = mul i32 [[A:%.*]], 3
+; CHECK-NEXT:    [[MUL:%.*]] = add i32 [[TMP1]], 9
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %add = or disjoint i32 %a, 3
+  %mul = mul nsw i32 %add, 3
+  ret i32 %mul
+}
+
 ; https://alive2.llvm.org/ce/z/XYpv9q
 define <2 x i32> @PR57278_shl_vec(<2 x i32> %v1) {
 ; CHECK-LABEL: @PR57278_shl_vec(