[llvm] [LoopPeel] Handle non-local instructions/arguments when updating exiting values (PR #142993)
Yingwei Zheng via llvm-commits
llvm-commits at lists.llvm.org
Thu Jun 5 09:04:44 PDT 2025
https://github.com/dtcxzyw updated https://github.com/llvm/llvm-project/pull/142993
>From d057a97cb1ddacbc501ea3bbd08e94f32ef7eaa9 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 5 Jun 2025 23:12:34 +0800
Subject: [PATCH 1/2] [LoopPeel] Handle non-local instructions/arguments when
updating exit values
---
llvm/lib/Transforms/Utils/LoopPeel.cpp | 6 ++-
.../unroll-and-peel-last-iteration.ll | 41 +++++++++++++++++++
2 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/Utils/LoopPeel.cpp b/llvm/lib/Transforms/Utils/LoopPeel.cpp
index bd025fddd0cf7..9149f71941db4 100644
--- a/llvm/lib/Transforms/Utils/LoopPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopPeel.cpp
@@ -1257,7 +1257,11 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, bool PeelLast, LoopInfo *LI,
// Now adjust users of the original exit values by replacing them with the
// exit value from the peeled iteration and remove them.
for (const auto &[P, E] : ExitValues) {
- P->replaceAllUsesWith(isa<Constant>(E) ? E : &*VMap.lookup(E));
+ Instruction *ExitInst = dyn_cast<Instruction>(E);
+ if (ExitInst && L->contains(ExitInst))
+ P->replaceAllUsesWith(&*VMap[ExitInst]);
+ else
+ P->replaceAllUsesWith(E);
P->eraseFromParent();
}
formLCSSA(*L, DT, LI, SE);
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll b/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
index 7d38c18d10667..f07afaf1b207f 100644
--- a/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
+++ b/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
@@ -71,6 +71,47 @@ exit:
ret i32 %1
}
+; Test case for https://github.com/llvm/llvm-project/issues/142895.
+
+define i32 @pr142895_exit_value_is_arg(i32 %arg) {
+entry:
+ br label %for.cond.preheader
+
+for.cond.preheader:
+ %indvar = phi i32 [ 0, %entry ], [ %inc, %for.cond.preheader ]
+ %cmp1 = icmp eq i32 %indvar, 32
+ %sel = select i1 %cmp1, i32 0, i32 0
+ %sub = sub i32 0, 0
+ %xor = xor i32 0, 0
+ %inc = add i32 %indvar, 1
+ %exitcond = icmp ne i32 %inc, 33
+ br i1 %exitcond, label %for.cond.preheader, label %for.cond.cleanup
+
+for.cond.cleanup:
+ %exit.lcssa = phi i32 [ %arg, %for.cond.preheader ]
+ ret i32 %exit.lcssa
+}
+
+define i32 @pr142895_exit_value_is_inst(i32 %arg) {
+entry:
+ %mul = mul i32 %arg, 7
+ br label %for.cond.preheader
+
+for.cond.preheader:
+ %indvar = phi i32 [ 0, %entry ], [ %inc, %for.cond.preheader ]
+ %cmp1 = icmp eq i32 %indvar, 32
+ %sel = select i1 %cmp1, i32 0, i32 0
+ %sub = sub i32 0, 0
+ %xor = xor i32 0, 0
+ %inc = add i32 %indvar, 1
+ %exitcond = icmp ne i32 %inc, 33
+ br i1 %exitcond, label %for.cond.preheader, label %for.cond.cleanup
+
+for.cond.cleanup:
+ %exit.lcssa = phi i32 [ %mul, %for.cond.preheader ]
+ ret i32 %exit.lcssa
+}
+
declare void @foo(i32)
;.
; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
>From e1c547542c4dda027205abffa38bfbc2846b980a Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Fri, 6 Jun 2025 00:04:25 +0800
Subject: [PATCH 2/2] [LoopPeel] Update tests. NFC.
---
.../unroll-and-peel-last-iteration.ll | 81 ++++++++++++++++---
1 file changed, 69 insertions(+), 12 deletions(-)
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll b/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
index f07afaf1b207f..bc20c59c3943b 100644
--- a/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
+++ b/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
@@ -74,41 +74,96 @@ exit:
; Test case for https://github.com/llvm/llvm-project/issues/142895.
define i32 @pr142895_exit_value_is_arg(i32 %arg) {
+; CHECK-LABEL: define i32 @pr142895_exit_value_is_arg(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*]]:
+; CHECK-NEXT: br label %[[LOOP:.*]]
+; CHECK: [[LOOP]]:
+; CHECK-NEXT: [[INDVAR:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[INC:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[INDVAR]], 1
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i32 [[INC]], 32
+; CHECK-NEXT: br i1 [[EXITCOND]], label %[[LOOP]], label %[[EXIT_PEEL_BEGIN:.*]], !llvm.loop [[LOOP2:![0-9]+]]
+; CHECK: [[EXIT_PEEL_BEGIN]]:
+; CHECK-NEXT: [[TMP0:%.*]] = phi i32 [ [[INC]], %[[LOOP]] ]
+; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
+; CHECK: [[LOOP_PEEL]]:
+; CHECK-NEXT: [[CMP1_PEEL:%.*]] = icmp eq i32 [[TMP0]], 32
+; CHECK-NEXT: [[SEL_PEEL:%.*]] = select i1 [[CMP1_PEEL]], i32 0, i32 0
+; CHECK-NEXT: [[SUB_PEEL:%.*]] = sub i32 0, 0
+; CHECK-NEXT: [[XOR_PEEL:%.*]] = xor i32 0, 0
+; CHECK-NEXT: [[INC_PEEL:%.*]] = add i32 [[TMP0]], 1
+; CHECK-NEXT: [[EXITCOND_PEEL:%.*]] = icmp ne i32 [[INC_PEEL]], 33
+; CHECK-NEXT: br i1 [[EXITCOND_PEEL]], label %[[EXIT_PEEL_NEXT:.*]], label %[[EXIT_PEEL_NEXT]]
+; CHECK: [[EXIT_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[LOOP_PEEL_NEXT:.*]]
+; CHECK: [[LOOP_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[EXIT:.*]]
+; CHECK: [[EXIT]]:
+; CHECK-NEXT: ret i32 [[ARG]]
+;
entry:
- br label %for.cond.preheader
+ br label %loop
-for.cond.preheader:
- %indvar = phi i32 [ 0, %entry ], [ %inc, %for.cond.preheader ]
+loop:
+ %indvar = phi i32 [ 0, %entry ], [ %inc, %loop ]
%cmp1 = icmp eq i32 %indvar, 32
%sel = select i1 %cmp1, i32 0, i32 0
%sub = sub i32 0, 0
%xor = xor i32 0, 0
%inc = add i32 %indvar, 1
%exitcond = icmp ne i32 %inc, 33
- br i1 %exitcond, label %for.cond.preheader, label %for.cond.cleanup
+ br i1 %exitcond, label %loop, label %exit
-for.cond.cleanup:
- %exit.lcssa = phi i32 [ %arg, %for.cond.preheader ]
+exit:
+ %exit.lcssa = phi i32 [ %arg, %loop ]
ret i32 %exit.lcssa
}
define i32 @pr142895_exit_value_is_inst(i32 %arg) {
+; CHECK-LABEL: define i32 @pr142895_exit_value_is_inst(
+; CHECK-SAME: i32 [[ARG:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*]]:
+; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[ARG]], 7
+; CHECK-NEXT: br label %[[LOOP:.*]]
+; CHECK: [[LOOP]]:
+; CHECK-NEXT: [[INDVAR:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[INC:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[INDVAR]], 1
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i32 [[INC]], 32
+; CHECK-NEXT: br i1 [[EXITCOND]], label %[[LOOP]], label %[[EXIT_PEEL_BEGIN:.*]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK: [[EXIT_PEEL_BEGIN]]:
+; CHECK-NEXT: [[TMP0:%.*]] = phi i32 [ [[INC]], %[[LOOP]] ]
+; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
+; CHECK: [[LOOP_PEEL]]:
+; CHECK-NEXT: [[CMP1_PEEL:%.*]] = icmp eq i32 [[TMP0]], 32
+; CHECK-NEXT: [[SEL_PEEL:%.*]] = select i1 [[CMP1_PEEL]], i32 0, i32 0
+; CHECK-NEXT: [[SUB_PEEL:%.*]] = sub i32 0, 0
+; CHECK-NEXT: [[XOR_PEEL:%.*]] = xor i32 0, 0
+; CHECK-NEXT: [[INC_PEEL:%.*]] = add i32 [[TMP0]], 1
+; CHECK-NEXT: [[EXITCOND_PEEL:%.*]] = icmp ne i32 [[INC_PEEL]], 33
+; CHECK-NEXT: br i1 [[EXITCOND_PEEL]], label %[[EXIT_PEEL_NEXT:.*]], label %[[EXIT_PEEL_NEXT]]
+; CHECK: [[EXIT_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[LOOP_PEEL_NEXT:.*]]
+; CHECK: [[LOOP_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[EXIT:.*]]
+; CHECK: [[EXIT]]:
+; CHECK-NEXT: ret i32 [[MUL]]
+;
entry:
%mul = mul i32 %arg, 7
- br label %for.cond.preheader
+ br label %loop
-for.cond.preheader:
- %indvar = phi i32 [ 0, %entry ], [ %inc, %for.cond.preheader ]
+loop:
+ %indvar = phi i32 [ 0, %entry ], [ %inc, %loop ]
%cmp1 = icmp eq i32 %indvar, 32
%sel = select i1 %cmp1, i32 0, i32 0
%sub = sub i32 0, 0
%xor = xor i32 0, 0
%inc = add i32 %indvar, 1
%exitcond = icmp ne i32 %inc, 33
- br i1 %exitcond, label %for.cond.preheader, label %for.cond.cleanup
+ br i1 %exitcond, label %loop, label %exit
-for.cond.cleanup:
- %exit.lcssa = phi i32 [ %mul, %for.cond.preheader ]
+exit:
+ %exit.lcssa = phi i32 [ %mul, %loop ]
ret i32 %exit.lcssa
}
@@ -116,4 +171,6 @@ declare void @foo(i32)
;.
; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
; CHECK: [[META1]] = !{!"llvm.loop.peeled.count", i32 1}
+; CHECK: [[LOOP2]] = distinct !{[[LOOP2]], [[META1]]}
+; CHECK: [[LOOP3]] = distinct !{[[LOOP3]], [[META1]]}
;.
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