[BasicAA][ValueTracking] Increase depth for underlying object search #143714
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This depth limits a linear search (rather than the usual potentially exponential one) and is not particularly important for compile-time in practice. The change in llvm#137297 is going to increase the length of GEP chains, so I'd like to increase this limit a bit to reduce the chance of regressions.
|
@llvm/pr-subscribers-llvm-analysis Author: Nikita Popov (nikic) ChangesThis depth limits a linear search (rather than the usual potentially exponential one) and is not particularly important for compile-time in practice. The change in #137297 is going to increase the length of GEP chains, so I'd like to increase this limit a bit to reduce the chance of regressions (dtcxzyw/llvm-opt-benchmark#2419 showed a 13% increase in SearchLimitReached). There is no particular significance to the new value of 10. Compile-time looks neutral: https://llvm-compile-time-tracker.com/compare.php?from=a72bcda1434c72f9db6687565a361479e0dde572&to=f5129a63ce2c543b07de49b0308d2adb2b600582&stat=instructions:u Full diff: https://github.com/llvm/llvm-project/pull/143714.diff 4 Files Affected:
diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 32ab9733d13c9..e215c90b5a72a 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -47,7 +47,7 @@ constexpr unsigned MaxAnalysisRecursionDepth = 6;
/// The max limit of the search depth in DecomposeGEPExpression() and
/// getUnderlyingObject().
-constexpr unsigned MaxLookupSearchDepth = 6;
+constexpr unsigned MaxLookupSearchDepth = 10;
/// Determine which bits of V are known to be either zero or one and return
/// them in the KnownZero/KnownOne bit sets.
diff --git a/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll b/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
index 23a96ebca8485..a256ececbe565 100644
--- a/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
+++ b/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
@@ -2,22 +2,22 @@
; CHECK-LABEL: Function: test
;; Before limit:
-; CHECK-DAG: MustAlias: i8* %gep.add5, i8* %gep.inc5
-; CHECK-DAG: NoAlias: i8* %gep.inc3, i8* %gep.inc5
-; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc5
+; CHECK-DAG: MustAlias: i8* %gep.add9, i8* %gep.inc9
+; CHECK-DAG: NoAlias: i8* %gep.inc7, i8* %gep.inc9
+; CHECK-DAG: NoAlias: i8* %gep.inc8, i8* %gep.inc9
;; At limit:
-; CHECK-DAG: MustAlias: i8* %gep.add6, i8* %gep.inc6
-; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc6
-; CHECK-DAG: NoAlias: i8* %gep.inc5, i8* %gep.inc6
+; CHECK-DAG: MustAlias: i8* %gep.add10, i8* %gep.inc10
+; CHECK-DAG: NoAlias: i8* %gep.inc10, i8* %gep.inc8
+; CHECK-DAG: NoAlias: i8* %gep.inc10, i8* %gep.inc9
;; After limit:
-; CHECK-DAG: MayAlias: i8* %gep.add7, i8* %gep.inc7
-; CHECK-DAG: MayAlias: i8* %gep.inc5, i8* %gep.inc7
-; CHECK-DAG: NoAlias: i8* %gep.inc6, i8* %gep.inc7
+; CHECK-DAG: MayAlias: i8* %gep.add11, i8* %gep.inc11
+; CHECK-DAG: MayAlias: i8* %gep.inc11, i8* %gep.inc9
+; CHECK-DAG: NoAlias: i8* %gep.inc10, i8* %gep.inc11
define void @test(ptr %base) {
- %gep.add5 = getelementptr i8, ptr %base, i64 5
- %gep.add6 = getelementptr i8, ptr %base, i64 6
- %gep.add7 = getelementptr i8, ptr %base, i64 7
+ %gep.add9 = getelementptr i8, ptr %base, i64 9
+ %gep.add10 = getelementptr i8, ptr %base, i64 10
+ %gep.add11 = getelementptr i8, ptr %base, i64 11
%gep.inc1 = getelementptr i8, ptr %base, i64 1
%gep.inc2 = getelementptr i8, ptr %gep.inc1, i64 1
@@ -26,15 +26,23 @@ define void @test(ptr %base) {
%gep.inc5 = getelementptr i8, ptr %gep.inc4, i64 1
%gep.inc6 = getelementptr i8, ptr %gep.inc5, i64 1
%gep.inc7 = getelementptr i8, ptr %gep.inc6, i64 1
+ %gep.inc8 = getelementptr i8, ptr %gep.inc7, i64 1
+ %gep.inc9 = getelementptr i8, ptr %gep.inc8, i64 1
+ %gep.inc10 = getelementptr i8, ptr %gep.inc9, i64 1
+ %gep.inc11 = getelementptr i8, ptr %gep.inc10, i64 1
- load i8, ptr %gep.add5
- load i8, ptr %gep.add6
- load i8, ptr %gep.add7
+ load i8, ptr %gep.add9
+ load i8, ptr %gep.add10
+ load i8, ptr %gep.add11
load i8, ptr %gep.inc3
load i8, ptr %gep.inc4
load i8, ptr %gep.inc5
load i8, ptr %gep.inc6
load i8, ptr %gep.inc7
+ load i8, ptr %gep.inc8
+ load i8, ptr %gep.inc9
+ load i8, ptr %gep.inc10
+ load i8, ptr %gep.inc11
ret void
}
diff --git a/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll b/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll
index abfdff79dc113..1d3512128678e 100644
--- a/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll
+++ b/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll
@@ -127,9 +127,12 @@ for_j.body:
%gepB7 = getelementptr inbounds i8, ptr %gepB6, i64 0
%gepB8 = getelementptr inbounds i8, ptr %gepB7, i64 0
%gepB9 = getelementptr inbounds i8, ptr %gepB8, i64 0
+ %gepB10 = getelementptr inbounds i8, ptr %gepB9, i64 0
+ %gepB11 = getelementptr inbounds i8, ptr %gepB10, i64 0
+ %gepB12 = getelementptr inbounds i8, ptr %gepB11, i64 0
%loadPrev = load i8, ptr %gepPrev, align 1
- %loadB = load i8, ptr %gepB9, align 1
+ %loadB = load i8, ptr %gepB12, align 1
%mul = mul i8 %loadPrev, %loadB
diff --git a/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll b/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll
index 54e9ee0918ae8..b7ba1b32238a7 100644
--- a/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll
+++ b/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll
@@ -3,15 +3,18 @@
define i32 @caller(ptr %p) {
; CHECK-LABEL: define i32 @caller(ptr %p) {
; CHECK-NEXT: call void @llvm.experimental.noalias.scope.decl(metadata [[META0:![0-9]+]])
-; CHECK-NEXT: [[P_8_I:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 8
-; CHECK-NEXT: [[V_I:%.*]] = load i32, ptr [[P_8_I]], align 4, !alias.scope !0
-; CHECK-NEXT: [[P_1_I:%.*]] = getelementptr i8, ptr [[P]], i64 1
+; CHECK-NEXT: [[P_11_I:%.*]] = getelementptr i8, ptr %p, i64 11
+; CHECK-NEXT: [[V_I:%.*]] = load i32, ptr [[P_11_I]], align 4, !alias.scope !0
+; CHECK-NEXT: [[P_1_I:%.*]] = getelementptr i8, ptr %p, i64 1
; CHECK-NEXT: [[P_2_I:%.*]] = getelementptr i8, ptr [[P_1_I]], i64 1
; CHECK-NEXT: [[P_3_I:%.*]] = getelementptr i8, ptr [[P_2_I]], i64 1
; CHECK-NEXT: [[P_4_I:%.*]] = getelementptr i8, ptr [[P_3_I]], i64 1
; CHECK-NEXT: [[P_5_I:%.*]] = getelementptr i8, ptr [[P_4_I]], i64 1
; CHECK-NEXT: [[P_6_I:%.*]] = getelementptr i8, ptr [[P_5_I]], i64 1
-; CHECK-NEXT: [[P_7_I:%.*]] = getelementptr i8, ptr [[P_6_I]], i64 1
+; CHECK-NEXT: [[P_7_I1:%.*]] = getelementptr i8, ptr [[P_6_I]], i64 1
+; CHECK-NEXT: [[P_8_I:%.*]] = getelementptr i8, ptr [[P_7_I1]], i64 1
+; CHECK-NEXT: [[P_9_I:%.*]] = getelementptr i8, ptr [[P_8_I]], i64 1
+; CHECK-NEXT: [[P_7_I:%.*]] = getelementptr i8, ptr [[P_9_I]], i64 1
; CHECK-NEXT: [[P_8_ALIAS_I:%.*]] = getelementptr i8, ptr [[P_7_I]], i64 1
; CHECK-NEXT: store i32 42, ptr [[P_8_ALIAS_I]], align 4
; CHECK-NEXT: ret i32 [[V_I]]
@@ -21,8 +24,8 @@ define i32 @caller(ptr %p) {
}
define internal i32 @callee(ptr noalias %p) {
- %p.8 = getelementptr i8, ptr %p, i64 8
- %v = load i32, ptr %p.8
+ %p.11 = getelementptr i8, ptr %p, i64 11
+ %v = load i32, ptr %p.11
%p.1 = getelementptr i8, ptr %p, i64 1
%p.2 = getelementptr i8, ptr %p.1, i64 1
%p.3 = getelementptr i8, ptr %p.2, i64 1
@@ -30,7 +33,10 @@ define internal i32 @callee(ptr noalias %p) {
%p.5 = getelementptr i8, ptr %p.4, i64 1
%p.6 = getelementptr i8, ptr %p.5, i64 1
%p.7 = getelementptr i8, ptr %p.6, i64 1
- %p.8.alias = getelementptr i8, ptr %p.7, i64 1
- store i32 42, ptr %p.8.alias
+ %p.8 = getelementptr i8, ptr %p.7, i64 1
+ %p.9 = getelementptr i8, ptr %p.8, i64 1
+ %p.10 = getelementptr i8, ptr %p.9, i64 1
+ %p.11.alias = getelementptr i8, ptr %p.10, i64 1
+ store i32 42, ptr %p.11.alias
ret i32 %v
}
|
|
@llvm/pr-subscribers-llvm-transforms Author: Nikita Popov (nikic) ChangesThis depth limits a linear search (rather than the usual potentially exponential one) and is not particularly important for compile-time in practice. The change in #137297 is going to increase the length of GEP chains, so I'd like to increase this limit a bit to reduce the chance of regressions (dtcxzyw/llvm-opt-benchmark#2419 showed a 13% increase in SearchLimitReached). There is no particular significance to the new value of 10. Compile-time looks neutral: https://llvm-compile-time-tracker.com/compare.php?from=a72bcda1434c72f9db6687565a361479e0dde572&to=f5129a63ce2c543b07de49b0308d2adb2b600582&stat=instructions:u Full diff: https://github.com/llvm/llvm-project/pull/143714.diff 4 Files Affected:
diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 32ab9733d13c9..e215c90b5a72a 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -47,7 +47,7 @@ constexpr unsigned MaxAnalysisRecursionDepth = 6;
/// The max limit of the search depth in DecomposeGEPExpression() and
/// getUnderlyingObject().
-constexpr unsigned MaxLookupSearchDepth = 6;
+constexpr unsigned MaxLookupSearchDepth = 10;
/// Determine which bits of V are known to be either zero or one and return
/// them in the KnownZero/KnownOne bit sets.
diff --git a/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll b/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
index 23a96ebca8485..a256ececbe565 100644
--- a/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
+++ b/llvm/test/Analysis/BasicAA/gep-decomposition-limit.ll
@@ -2,22 +2,22 @@
; CHECK-LABEL: Function: test
;; Before limit:
-; CHECK-DAG: MustAlias: i8* %gep.add5, i8* %gep.inc5
-; CHECK-DAG: NoAlias: i8* %gep.inc3, i8* %gep.inc5
-; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc5
+; CHECK-DAG: MustAlias: i8* %gep.add9, i8* %gep.inc9
+; CHECK-DAG: NoAlias: i8* %gep.inc7, i8* %gep.inc9
+; CHECK-DAG: NoAlias: i8* %gep.inc8, i8* %gep.inc9
;; At limit:
-; CHECK-DAG: MustAlias: i8* %gep.add6, i8* %gep.inc6
-; CHECK-DAG: NoAlias: i8* %gep.inc4, i8* %gep.inc6
-; CHECK-DAG: NoAlias: i8* %gep.inc5, i8* %gep.inc6
+; CHECK-DAG: MustAlias: i8* %gep.add10, i8* %gep.inc10
+; CHECK-DAG: NoAlias: i8* %gep.inc10, i8* %gep.inc8
+; CHECK-DAG: NoAlias: i8* %gep.inc10, i8* %gep.inc9
;; After limit:
-; CHECK-DAG: MayAlias: i8* %gep.add7, i8* %gep.inc7
-; CHECK-DAG: MayAlias: i8* %gep.inc5, i8* %gep.inc7
-; CHECK-DAG: NoAlias: i8* %gep.inc6, i8* %gep.inc7
+; CHECK-DAG: MayAlias: i8* %gep.add11, i8* %gep.inc11
+; CHECK-DAG: MayAlias: i8* %gep.inc11, i8* %gep.inc9
+; CHECK-DAG: NoAlias: i8* %gep.inc10, i8* %gep.inc11
define void @test(ptr %base) {
- %gep.add5 = getelementptr i8, ptr %base, i64 5
- %gep.add6 = getelementptr i8, ptr %base, i64 6
- %gep.add7 = getelementptr i8, ptr %base, i64 7
+ %gep.add9 = getelementptr i8, ptr %base, i64 9
+ %gep.add10 = getelementptr i8, ptr %base, i64 10
+ %gep.add11 = getelementptr i8, ptr %base, i64 11
%gep.inc1 = getelementptr i8, ptr %base, i64 1
%gep.inc2 = getelementptr i8, ptr %gep.inc1, i64 1
@@ -26,15 +26,23 @@ define void @test(ptr %base) {
%gep.inc5 = getelementptr i8, ptr %gep.inc4, i64 1
%gep.inc6 = getelementptr i8, ptr %gep.inc5, i64 1
%gep.inc7 = getelementptr i8, ptr %gep.inc6, i64 1
+ %gep.inc8 = getelementptr i8, ptr %gep.inc7, i64 1
+ %gep.inc9 = getelementptr i8, ptr %gep.inc8, i64 1
+ %gep.inc10 = getelementptr i8, ptr %gep.inc9, i64 1
+ %gep.inc11 = getelementptr i8, ptr %gep.inc10, i64 1
- load i8, ptr %gep.add5
- load i8, ptr %gep.add6
- load i8, ptr %gep.add7
+ load i8, ptr %gep.add9
+ load i8, ptr %gep.add10
+ load i8, ptr %gep.add11
load i8, ptr %gep.inc3
load i8, ptr %gep.inc4
load i8, ptr %gep.inc5
load i8, ptr %gep.inc6
load i8, ptr %gep.inc7
+ load i8, ptr %gep.inc8
+ load i8, ptr %gep.inc9
+ load i8, ptr %gep.inc10
+ load i8, ptr %gep.inc11
ret void
}
diff --git a/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll b/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll
index abfdff79dc113..1d3512128678e 100644
--- a/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll
+++ b/llvm/test/Analysis/LoopAccessAnalysis/underlying-objects-2.ll
@@ -127,9 +127,12 @@ for_j.body:
%gepB7 = getelementptr inbounds i8, ptr %gepB6, i64 0
%gepB8 = getelementptr inbounds i8, ptr %gepB7, i64 0
%gepB9 = getelementptr inbounds i8, ptr %gepB8, i64 0
+ %gepB10 = getelementptr inbounds i8, ptr %gepB9, i64 0
+ %gepB11 = getelementptr inbounds i8, ptr %gepB10, i64 0
+ %gepB12 = getelementptr inbounds i8, ptr %gepB11, i64 0
%loadPrev = load i8, ptr %gepPrev, align 1
- %loadB = load i8, ptr %gepB9, align 1
+ %loadB = load i8, ptr %gepB12, align 1
%mul = mul i8 %loadPrev, %loadB
diff --git a/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll b/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll
index 54e9ee0918ae8..b7ba1b32238a7 100644
--- a/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll
+++ b/llvm/test/Transforms/Inline/inline-noalias-unidentify-object.ll
@@ -3,15 +3,18 @@
define i32 @caller(ptr %p) {
; CHECK-LABEL: define i32 @caller(ptr %p) {
; CHECK-NEXT: call void @llvm.experimental.noalias.scope.decl(metadata [[META0:![0-9]+]])
-; CHECK-NEXT: [[P_8_I:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 8
-; CHECK-NEXT: [[V_I:%.*]] = load i32, ptr [[P_8_I]], align 4, !alias.scope !0
-; CHECK-NEXT: [[P_1_I:%.*]] = getelementptr i8, ptr [[P]], i64 1
+; CHECK-NEXT: [[P_11_I:%.*]] = getelementptr i8, ptr %p, i64 11
+; CHECK-NEXT: [[V_I:%.*]] = load i32, ptr [[P_11_I]], align 4, !alias.scope !0
+; CHECK-NEXT: [[P_1_I:%.*]] = getelementptr i8, ptr %p, i64 1
; CHECK-NEXT: [[P_2_I:%.*]] = getelementptr i8, ptr [[P_1_I]], i64 1
; CHECK-NEXT: [[P_3_I:%.*]] = getelementptr i8, ptr [[P_2_I]], i64 1
; CHECK-NEXT: [[P_4_I:%.*]] = getelementptr i8, ptr [[P_3_I]], i64 1
; CHECK-NEXT: [[P_5_I:%.*]] = getelementptr i8, ptr [[P_4_I]], i64 1
; CHECK-NEXT: [[P_6_I:%.*]] = getelementptr i8, ptr [[P_5_I]], i64 1
-; CHECK-NEXT: [[P_7_I:%.*]] = getelementptr i8, ptr [[P_6_I]], i64 1
+; CHECK-NEXT: [[P_7_I1:%.*]] = getelementptr i8, ptr [[P_6_I]], i64 1
+; CHECK-NEXT: [[P_8_I:%.*]] = getelementptr i8, ptr [[P_7_I1]], i64 1
+; CHECK-NEXT: [[P_9_I:%.*]] = getelementptr i8, ptr [[P_8_I]], i64 1
+; CHECK-NEXT: [[P_7_I:%.*]] = getelementptr i8, ptr [[P_9_I]], i64 1
; CHECK-NEXT: [[P_8_ALIAS_I:%.*]] = getelementptr i8, ptr [[P_7_I]], i64 1
; CHECK-NEXT: store i32 42, ptr [[P_8_ALIAS_I]], align 4
; CHECK-NEXT: ret i32 [[V_I]]
@@ -21,8 +24,8 @@ define i32 @caller(ptr %p) {
}
define internal i32 @callee(ptr noalias %p) {
- %p.8 = getelementptr i8, ptr %p, i64 8
- %v = load i32, ptr %p.8
+ %p.11 = getelementptr i8, ptr %p, i64 11
+ %v = load i32, ptr %p.11
%p.1 = getelementptr i8, ptr %p, i64 1
%p.2 = getelementptr i8, ptr %p.1, i64 1
%p.3 = getelementptr i8, ptr %p.2, i64 1
@@ -30,7 +33,10 @@ define internal i32 @callee(ptr noalias %p) {
%p.5 = getelementptr i8, ptr %p.4, i64 1
%p.6 = getelementptr i8, ptr %p.5, i64 1
%p.7 = getelementptr i8, ptr %p.6, i64 1
- %p.8.alias = getelementptr i8, ptr %p.7, i64 1
- store i32 42, ptr %p.8.alias
+ %p.8 = getelementptr i8, ptr %p.7, i64 1
+ %p.9 = getelementptr i8, ptr %p.8, i64 1
+ %p.10 = getelementptr i8, ptr %p.9, i64 1
+ %p.11.alias = getelementptr i8, ptr %p.10, i64 1
+ store i32 42, ptr %p.11.alias
ret i32 %v
}
|
|
basicaa.SearchLimitReached 40216 -> 5083 -87.36% |
tomtor
pushed a commit
to tomtor/llvm-project
that referenced
this pull request
Jun 14, 2025
…lvm#143714) This depth limits a linear search (rather than the usual potentially exponential one) and is not particularly important for compile-time in practice. The change in llvm#137297 is going to increase the length of GEP chains, so I'd like to increase this limit a bit to reduce the chance of regressions (dtcxzyw/llvm-opt-benchmark#2419 showed a 13% increase in SearchLimitReached). There is no particular significance to the new value of 10. Compile-time is neutral.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This depth limits a linear search (rather than the usual potentially exponential one) and is not particularly important for compile-time in practice.
The change in #137297 is going to increase the length of GEP chains, so I'd like to increase this limit a bit to reduce the chance of regressions (dtcxzyw/llvm-opt-benchmark#2419 showed a 13% increase in SearchLimitReached). There is no particular significance to the new value of 10.
Compile-time looks neutral: https://llvm-compile-time-tracker.com/compare.php?from=a72bcda1434c72f9db6687565a361479e0dde572&to=f5129a63ce2c543b07de49b0308d2adb2b600582&stat=instructions:u