[PATCH] D132658: [InstCombine] Distributive or+mul with const operand

[Allen zhong via Phabricator via llvm-commits]

Allen updated this revision to Diff 455790.
Allen added a comment.

address the comment


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D132658/new/

https://reviews.llvm.org/D132658

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


Index: llvm/test/Transforms/InstCombine/mul.ll
===================================================================
--- llvm/test/Transforms/InstCombine/mul.ll
+++ llvm/test/Transforms/InstCombine/mul.ll
@@ -624,6 +624,58 @@
   ret i32 %mul
 }
 
+define i32 @PR57278_shl(i32 %a) {
+; CHECK-LABEL: @PR57278_shl(
+; CHECK-NEXT:    [[TMP1:%.*]] = mul i32 [[A:%.*]], 12
+; CHECK-NEXT:    [[MUL:%.*]] = add i32 [[TMP1]], 9
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %shl = shl nsw i32 %a, 2
+  %add = or i32 %shl, 3
+  %mul = mul nsw i32 %add, 3
+  ret i32 %mul
+}
+
+; Negative test: Have common bits set
+define i32 @PR57278_shl_1(i32 %a) {
+; CHECK-LABEL: @PR57278_shl_1(
+; CHECK-NEXT:    [[SHL:%.*]] = shl nsw i32 [[A:%.*]], 2
+; CHECK-NEXT:    [[ADD:%.*]] = or i32 [[SHL]], 4
+; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i32 [[ADD]], 3
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %shl = shl nsw i32 %a, 2
+  %add = or i32 %shl, 4
+  %mul = mul nsw i32 %add, 3
+  ret i32 %mul
+}
+
+define i32 @PR57278_mul(i32 %a) {
+; CHECK-LABEL: @PR57278_mul(
+; CHECK-NEXT:    [[TMP1:%.*]] = mul i32 [[A:%.*]], 36
+; CHECK-NEXT:    [[MUL:%.*]] = add i32 [[TMP1]], 9
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %mul0 = mul nsw i32 %a, 12
+  %add = or i32 %mul0, 3
+  %mul = mul nsw i32 %add, 3
+  ret i32 %mul
+}
+
+; Negative test: Have common bits set
+define i32 @PR57278_mul_1(i32 %a) {
+; CHECK-LABEL: @PR57278_mul_1(
+; CHECK-NEXT:    [[MUL0:%.*]] = mul nsw i32 [[A:%.*]], 12
+; CHECK-NEXT:    [[ADD:%.*]] = or i32 [[MUL0]], 4
+; CHECK-NEXT:    [[MUL:%.*]] = mul nsw i32 [[ADD]], 3
+; CHECK-NEXT:    ret i32 [[MUL]]
+;
+  %mul0 = mul nsw i32 %a, 12
+  %add = or i32 %mul0, 4
+  %mul = mul nsw i32 %add, 3
+  ret i32 %mul
+}
+
 define <2 x i1> @test21(<2 x i1> %A, <2 x i1> %B) {
 ; CHECK-LABEL: @test21(
 ; CHECK-NEXT:    [[C:%.*]] = and <2 x i1> [[A:%.*]], [[B:%.*]]
Index: llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -221,11 +221,14 @@
     return replaceInstUsesWith(I, FoldedMul);
 
   // Simplify mul instructions with a constant RHS.
-  if (isa<Constant>(Op1)) {
+  if (match(Op1, m_ImmConstant())) {
     // Canonicalize (X+C1)*CI -> X*CI+C1*CI.
+    // Canonicalize (X|C1)*CI -> X*CI+C1*CI.
     Value *X;
     Constant *C1;
-    if (match(Op0, m_OneUse(m_Add(m_Value(X), m_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, DL))) {
       Value *Mul = Builder.CreateMul(C1, Op1);
       // Only go forward with the transform if C1*CI simplifies to a tidier
       // constant.


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