[llvm] 2be8bea - Revert "[InstCombine] Add reverse of ((X << nuw Z) sub nuw Y) >>u exact Z --> X sub nuw (Y >>u exact Z) (#91386)"
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Sun May 26 23:32:51 PDT 2024
Author: Nikita Popov
Date: 2024-05-27T08:28:35+02:00
New Revision: 2be8bea1b7bbd16f745d690940b1244bf9ac4233
URL: https://github.com/llvm/llvm-project/commit/2be8bea1b7bbd16f745d690940b1244bf9ac4233
DIFF: https://github.com/llvm/llvm-project/commit/2be8bea1b7bbd16f745d690940b1244bf9ac4233.diff
LOG: Revert "[InstCombine] Add reverse of ((X << nuw Z) sub nuw Y) >>u exact Z --> X sub nuw (Y >>u exact Z) (#91386)"
This reverts commit c42c32088bdb03e39ed24f4800a447d4cbb788f2.
PR merged without review.
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
llvm/test/Transforms/InstCombine/lshr.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 01b1736ae5af8..4f91993750fd2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -1275,17 +1275,6 @@ Instruction *InstCombinerImpl::visitLShr(BinaryOperator &I) {
return NewSub;
}
- // (sub nuw X, (Y << nuw Z)) >>u exact Z --> (X >>u exact Z) sub nuw Y
- if (I.isExact() &&
- match(Op0, m_OneUse(m_NUWSub(m_Value(X),
- m_NUWShl(m_Value(Y), m_Specific(Op1)))))) {
- Value *NewLshr = Builder.CreateLShr(X, Op1, "", /*isExact=*/true);
- auto *NewSub = BinaryOperator::CreateNUWSub(NewLshr, Y);
- NewSub->setHasNoSignedWrap(
- cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap());
- return NewSub;
- }
-
auto isSuitableBinOpcode = [](Instruction::BinaryOps BinOpcode) {
switch (BinOpcode) {
default:
diff --git a/llvm/test/Transforms/InstCombine/lshr.ll b/llvm/test/Transforms/InstCombine/lshr.ll
index 8ff2299db6c18..dfdb6c7b4b268 100644
--- a/llvm/test/Transforms/InstCombine/lshr.ll
+++ b/llvm/test/Transforms/InstCombine/lshr.ll
@@ -466,33 +466,6 @@ define i32 @shl_sub_lshr(i32 %x, i32 %c, i32 %y) {
ret i32 %lshr
}
-define i32 @shl_sub_lshr_reverse(i32 %x, i32 %c, i32 %y) {
-; CHECK-LABEL: @shl_sub_lshr_reverse(
-; CHECK-NEXT: [[TMP1:%.*]] = lshr exact i32 [[Y:%.*]], [[C:%.*]]
-; CHECK-NEXT: [[LSHR:%.*]] = sub nuw nsw i32 [[TMP1]], [[X:%.*]]
-; CHECK-NEXT: ret i32 [[LSHR]]
-;
- %shl = shl nuw i32 %x, %c
- %sub = sub nuw nsw i32 %y, %shl
- %lshr = lshr exact i32 %sub, %c
- ret i32 %lshr
-}
-
-; Negative test
-
-define i32 @shl_sub_lshr_reverse_no_exact(i32 %x, i32 %c, i32 %y) {
-; CHECK-LABEL: @shl_sub_lshr_reverse_no_exact(
-; CHECK-NEXT: [[SHL:%.*]] = shl nuw i32 [[X:%.*]], [[C:%.*]]
-; CHECK-NEXT: [[SUB:%.*]] = sub nuw nsw i32 [[Y:%.*]], [[SHL]]
-; CHECK-NEXT: [[LSHR:%.*]] = lshr i32 [[SUB]], [[C]]
-; CHECK-NEXT: ret i32 [[LSHR]]
-;
- %shl = shl nuw i32 %x, %c
- %sub = sub nuw nsw i32 %y, %shl
- %lshr = lshr i32 %sub, %c
- ret i32 %lshr
-}
-
define i32 @shl_or_lshr(i32 %x, i32 %c, i32 %y) {
; CHECK-LABEL: @shl_or_lshr(
; CHECK-NEXT: [[TMP1:%.*]] = lshr i32 [[Y:%.*]], [[C:%.*]]
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