[PATCH] D153148: [InstCombine] Fold `(-1 + A) & B` into `A ? 0 : B` where A is effectively a bool

[Yingwei Zheng via Phabricator via llvm-commits]

dtcxzyw updated this revision to Diff 537126.
dtcxzyw added a comment.

Rebase on D154187 <https://reviews.llvm.org/D154187>


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D153148/new/

https://reviews.llvm.org/D153148

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/test/Transforms/InstCombine/binop-cast.ll


Index: llvm/test/Transforms/InstCombine/binop-cast.ll
===================================================================
--- llvm/test/Transforms/InstCombine/binop-cast.ll
+++ llvm/test/Transforms/InstCombine/binop-cast.ll
@@ -261,9 +261,8 @@
 define i64 @PR63321(ptr %ptr, i64 %c) {
 ; CHECK-LABEL: @PR63321(
 ; CHECK-NEXT:    [[VAL:%.*]] = load i8, ptr [[PTR:%.*]], align 1, !range [[RNG0:![0-9]+]]
-; CHECK-NEXT:    [[RHS:%.*]] = zext i8 [[VAL]] to i64
-; CHECK-NEXT:    [[MASK:%.*]] = add nsw i64 [[RHS]], -1
-; CHECK-NEXT:    [[RES:%.*]] = and i64 [[MASK]], [[C:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i8 [[VAL]], 0
+; CHECK-NEXT:    [[RES:%.*]] = select i1 [[TMP1]], i64 [[C:%.*]], i64 0
 ; CHECK-NEXT:    ret i64 [[RES]]
 ;
   %val = load i8, ptr %ptr, align 1, !range !{i8 0, i8 2}
@@ -304,8 +303,8 @@
 define i32 @and_add_bool_no_fold(i32 %y) {
 ; CHECK-LABEL: @and_add_bool_no_fold(
 ; CHECK-NEXT:    [[X:%.*]] = and i32 [[Y:%.*]], 1
-; CHECK-NEXT:    [[MASK:%.*]] = add nsw i32 [[X]], -1
-; CHECK-NEXT:    [[RES:%.*]] = and i32 [[MASK]], [[Y]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[X]], 0
+; CHECK-NEXT:    [[RES:%.*]] = select i1 [[TMP1]], i32 [[Y]], i32 0
 ; CHECK-NEXT:    ret i32 [[RES]]
 ;
   %x = and i32 %y, 1
Index: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2589,23 +2589,29 @@
   //       with binop identity constant. But creating a select with non-constant
   //       arm may not be reversible due to poison semantics. Is that a good
   //       canonicalization?
-  Value *A;
-  if (match(Op0, m_OneUse(m_SExt(m_Value(A)))) &&
-      A->getType()->isIntOrIntVectorTy(1))
-    return SelectInst::Create(A, Op1, Constant::getNullValue(Ty));
-  if (match(Op1, m_OneUse(m_SExt(m_Value(A)))) &&
+  Value *A, *B;
+  if (match(&I, m_c_And(m_OneUse(m_SExt(m_Value(A))), m_Value(B))) &&
       A->getType()->isIntOrIntVectorTy(1))
-    return SelectInst::Create(A, Op0, Constant::getNullValue(Ty));
+    return SelectInst::Create(A, B, Constant::getNullValue(Ty));
 
   // Similarly, a 'not' of the bool translates to a swap of the select arms:
-  // ~sext(A) & Op1 --> A ? 0 : Op1
-  // Op0 & ~sext(A) --> A ? 0 : Op0
-  if (match(Op0, m_Not(m_SExt(m_Value(A)))) &&
-      A->getType()->isIntOrIntVectorTy(1))
-    return SelectInst::Create(A, Constant::getNullValue(Ty), Op1);
-  if (match(Op1, m_Not(m_SExt(m_Value(A)))) &&
+  // ~sext(A) & B / B & ~sext(A) --> A ? 0 : B
+  if (match(&I, m_c_And(m_Not(m_SExt(m_Value(A))), m_Value(B))) &&
       A->getType()->isIntOrIntVectorTy(1))
-    return SelectInst::Create(A, Constant::getNullValue(Ty), Op0);
+    return SelectInst::Create(A, Constant::getNullValue(Ty), B);
+
+  // (-1 + A) & B --> A ? 0 : B where A is effectively a bool (zext of i1/<N x
+  // i1>, or inst with !range {0, 2}).
+  if (match(&I, m_c_And(m_OneUse(m_Add(m_ZExtOrSelf(m_Value(A)), m_AllOnes())),
+                        m_Value(B)))) {
+    if (A->getType()->isIntOrIntVectorTy(1))
+      return SelectInst::Create(A, Constant::getNullValue(Ty), B);
+    if (computeKnownBits(A, /* Depth */ 0, &I).countMaxActiveBits() <= 1) {
+      return SelectInst::Create(
+          Builder.CreateICmpEQ(A, Constant::getNullValue(A->getType())), B,
+          Constant::getNullValue(Ty));
+    }
+  }
 
   // (iN X s>> (N-1)) & Y --> (X s< 0) ? Y : 0 -- with optional sext
   if (match(&I, m_c_And(m_OneUse(m_SExtOrSelf(


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D153148.537126.patch
Type: text/x-patch
Size: 3577 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230704/82b1854f/attachment.bin>