[LV] Only check isVectorizableEarlyExitLoop with multiple exits. #121994
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Currently we emit early-exit related debug messages/remarks even when there is a single exit. Update to only check isVectorizableEarlyExitLoop if there isn't a single exit block.
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@llvm/pr-subscribers-vectorizers Author: Florian Hahn (fhahn) ChangesCurrently we emit early-exit related debug messages/remarks even when there is a single exit. Update to only check isVectorizableEarlyExitLoop if there isn't a single exit block. Full diff: https://github.com/llvm/llvm-project/pull/121994.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
index cb0b4641b6492b..b11406bb0f390b 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -1784,14 +1784,23 @@ bool LoopVectorizationLegality::canVectorize(bool UseVPlanNativePath) {
HasUncountableEarlyExit = false;
if (isa<SCEVCouldNotCompute>(PSE.getBackedgeTakenCount())) {
- HasUncountableEarlyExit = true;
- if (!isVectorizableEarlyExitLoop()) {
- UncountableExitingBlocks.clear();
- HasUncountableEarlyExit = false;
+ if (TheLoop->getExitingBlock()) {
+ reportVectorizationFailure("Cannot vectorize uncountable loop",
+ "UnsupportedUncountableLoop", ORE, TheLoop);
if (DoExtraAnalysis)
Result = false;
else
return false;
+ } else {
+ HasUncountableEarlyExit = true;
+ if (!isVectorizableEarlyExitLoop()) {
+ UncountableExitingBlocks.clear();
+ HasUncountableEarlyExit = false;
+ if (DoExtraAnalysis)
+ Result = false;
+ else
+ return false;
+ }
}
}
diff --git a/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll b/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
index 4c0317e300f190..70134fa6bc78d6 100644
--- a/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
+++ b/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
@@ -12,7 +12,7 @@
; }
; }
; File, line, and column should match those specified in the metadata
-; CHECK: remark: source.cpp:5:9: loop not vectorized: Cannot vectorize early exit loop
+; CHECK: remark: source.cpp:5:9: loop not vectorized: Cannot vectorize uncountable loop
; CHECK: remark: source.cpp:5:9: loop not vectorized
; void test_disabled(int *A, int Length) {
@@ -46,12 +46,12 @@
; YAML: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
-; YAML-NEXT: Name: EarlyExitNotLatchPredecessor
+; YAML-NEXT: Name: UnsupportedUncountableLoop
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 5, Column: 9 }
; YAML-NEXT: Function: _Z4testPii
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
-; YAML-NEXT: - String: Cannot vectorize early exit loop
+; YAML-NEXT: - String: Cannot vectorize uncountable loop
; YAML-NEXT: ...
; YAML-NEXT: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
@@ -117,12 +117,12 @@
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
-; YAML-NEXT: Name: EarlyExitNotLatchPredecessor
+; YAML-NEXT: Name: UnsupportedUncountableLoop
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 27, Column: 3 }
; YAML-NEXT: Function: test_multiple_failures
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
-; YAML-NEXT: - String: Cannot vectorize early exit loop
+; YAML-NEXT: - String: Cannot vectorize uncountable loop
; YAML-NEXT: ...
; YAML: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
diff --git a/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll b/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
index 8df0eaec6a8c9d..6d365b9d77e80b 100644
--- a/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
+++ b/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
@@ -357,7 +357,7 @@ loop.end:
define i64 @uncountable_exit_infinite_loop() {
; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_infinite_loop'
-; CHECK: LV: Not vectorizing: Cannot determine exact exit count for latch block.
+; CHECK: LV: Not vectorizing: Cannot vectorize uncountable loop.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
diff --git a/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll b/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll
index 252061335e7365..c3958262f0af89 100644
--- a/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll
+++ b/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll
@@ -1,17 +1,17 @@
; REQUIRES: asserts
-; RUN: opt -p loop-vectorize -debug %s 2>&1 | FileCheck %s
+; RUN: opt -p loop-vectorize -debug-only=loop-vectorize -S %s 2>&1 | FileCheck %s
; CHECK-LABEL: LV: Checking a loop in 'latch_exit_cannot_compute_btc_due_to_step'
; CHECK: LV: Did not find one integer induction var.
-; CHECK-NEXT: LV: Not vectorizing: Early exit is not the latch predecessor.
+; CHECK-NEXT: LV: Not vectorizing: Cannot vectorize uncountable loop.
; CHECK-NEXT: LV: Interleaving disabled by the pass manager
; CHECK-NEXT: LV: Not vectorizing: Cannot prove legality.
; CHECK-LABEL: LV: Checking a loop in 'header_exit_cannot_compute_btc_due_to_step'
; CHECK: LV: Found an induction variable.
; CHECK-NEXT: LV: Did not find one integer induction var.
-; CHECK-NEXT: LV: Not vectorizing: Cannot determine exact exit count for latch block.
+; CHECK-NEXT: LV: Not vectorizing: Cannot vectorize uncountable loop.
; CHECK-NEXT: LV: Interleaving disabled by the pass manager
; CHECK-NEXT: LV: Not vectorizing: Cannot prove legality.
|
Member
|
@llvm/pr-subscribers-llvm-transforms Author: Florian Hahn (fhahn) ChangesCurrently we emit early-exit related debug messages/remarks even when there is a single exit. Update to only check isVectorizableEarlyExitLoop if there isn't a single exit block. Full diff: https://github.com/llvm/llvm-project/pull/121994.diff 4 Files Affected:
diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
index cb0b4641b6492b..b11406bb0f390b 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -1784,14 +1784,23 @@ bool LoopVectorizationLegality::canVectorize(bool UseVPlanNativePath) {
HasUncountableEarlyExit = false;
if (isa<SCEVCouldNotCompute>(PSE.getBackedgeTakenCount())) {
- HasUncountableEarlyExit = true;
- if (!isVectorizableEarlyExitLoop()) {
- UncountableExitingBlocks.clear();
- HasUncountableEarlyExit = false;
+ if (TheLoop->getExitingBlock()) {
+ reportVectorizationFailure("Cannot vectorize uncountable loop",
+ "UnsupportedUncountableLoop", ORE, TheLoop);
if (DoExtraAnalysis)
Result = false;
else
return false;
+ } else {
+ HasUncountableEarlyExit = true;
+ if (!isVectorizableEarlyExitLoop()) {
+ UncountableExitingBlocks.clear();
+ HasUncountableEarlyExit = false;
+ if (DoExtraAnalysis)
+ Result = false;
+ else
+ return false;
+ }
}
}
diff --git a/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll b/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
index 4c0317e300f190..70134fa6bc78d6 100644
--- a/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
+++ b/llvm/test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
@@ -12,7 +12,7 @@
; }
; }
; File, line, and column should match those specified in the metadata
-; CHECK: remark: source.cpp:5:9: loop not vectorized: Cannot vectorize early exit loop
+; CHECK: remark: source.cpp:5:9: loop not vectorized: Cannot vectorize uncountable loop
; CHECK: remark: source.cpp:5:9: loop not vectorized
; void test_disabled(int *A, int Length) {
@@ -46,12 +46,12 @@
; YAML: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
-; YAML-NEXT: Name: EarlyExitNotLatchPredecessor
+; YAML-NEXT: Name: UnsupportedUncountableLoop
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 5, Column: 9 }
; YAML-NEXT: Function: _Z4testPii
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
-; YAML-NEXT: - String: Cannot vectorize early exit loop
+; YAML-NEXT: - String: Cannot vectorize uncountable loop
; YAML-NEXT: ...
; YAML-NEXT: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
@@ -117,12 +117,12 @@
; YAML-NEXT: ...
; YAML-NEXT: --- !Analysis
; YAML-NEXT: Pass: loop-vectorize
-; YAML-NEXT: Name: EarlyExitNotLatchPredecessor
+; YAML-NEXT: Name: UnsupportedUncountableLoop
; YAML-NEXT: DebugLoc: { File: source.cpp, Line: 27, Column: 3 }
; YAML-NEXT: Function: test_multiple_failures
; YAML-NEXT: Args:
; YAML-NEXT: - String: 'loop not vectorized: '
-; YAML-NEXT: - String: Cannot vectorize early exit loop
+; YAML-NEXT: - String: Cannot vectorize uncountable loop
; YAML-NEXT: ...
; YAML: --- !Missed
; YAML-NEXT: Pass: loop-vectorize
diff --git a/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll b/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
index 8df0eaec6a8c9d..6d365b9d77e80b 100644
--- a/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
+++ b/llvm/test/Transforms/LoopVectorize/early_exit_legality.ll
@@ -357,7 +357,7 @@ loop.end:
define i64 @uncountable_exit_infinite_loop() {
; CHECK-LABEL: LV: Checking a loop in 'uncountable_exit_infinite_loop'
-; CHECK: LV: Not vectorizing: Cannot determine exact exit count for latch block.
+; CHECK: LV: Not vectorizing: Cannot vectorize uncountable loop.
entry:
%p1 = alloca [1024 x i8]
%p2 = alloca [1024 x i8]
diff --git a/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll b/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll
index 252061335e7365..c3958262f0af89 100644
--- a/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll
+++ b/llvm/test/Transforms/LoopVectorize/uncountable-single-exit-loops.ll
@@ -1,17 +1,17 @@
; REQUIRES: asserts
-; RUN: opt -p loop-vectorize -debug %s 2>&1 | FileCheck %s
+; RUN: opt -p loop-vectorize -debug-only=loop-vectorize -S %s 2>&1 | FileCheck %s
; CHECK-LABEL: LV: Checking a loop in 'latch_exit_cannot_compute_btc_due_to_step'
; CHECK: LV: Did not find one integer induction var.
-; CHECK-NEXT: LV: Not vectorizing: Early exit is not the latch predecessor.
+; CHECK-NEXT: LV: Not vectorizing: Cannot vectorize uncountable loop.
; CHECK-NEXT: LV: Interleaving disabled by the pass manager
; CHECK-NEXT: LV: Not vectorizing: Cannot prove legality.
; CHECK-LABEL: LV: Checking a loop in 'header_exit_cannot_compute_btc_due_to_step'
; CHECK: LV: Found an induction variable.
; CHECK-NEXT: LV: Did not find one integer induction var.
-; CHECK-NEXT: LV: Not vectorizing: Cannot determine exact exit count for latch block.
+; CHECK-NEXT: LV: Not vectorizing: Cannot vectorize uncountable loop.
; CHECK-NEXT: LV: Interleaving disabled by the pass manager
; CHECK-NEXT: LV: Not vectorizing: Cannot prove legality.
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preames
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Jan 7, 2025
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preames
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LGTM
It's worth noting that the style of logic used by the early exit reasoning could in theory vectorize some single exit loops which have a countable upper bound, but not an exact countable exit. Said differently, we could execute additional iterations when safe to do so. The current code doesn't do so, but we could reasonable extend it (in some future patch).
david-arm
approved these changes
Jan 8, 2025
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david-arm
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david-arm
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LGTM! Thanks for fixing this.
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…exits. (#121994) Currently we emit early-exit related debug messages/remarks even when there is a single exit. Update to only check isVectorizableEarlyExitLoop if there isn't a single exit block. PR: llvm/llvm-project#121994
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Currently we emit early-exit related debug messages/remarks even when there is a single exit. Update to only check isVectorizableEarlyExitLoop if there isn't a single exit block.