[Loads] Also consider getPointerAlignment when checking assumptions. #120916
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@llvm/pr-subscribers-llvm-analysis @llvm/pr-subscribers-llvm-transforms Author: Florian Hahn (fhahn) ChangesAlso use isAligned when trying to use alignment and dereferenceable assumptions. This catches cases where dereferencable is known via the assumption but alignment is known via isAligned (e.g. via argument attribute or align of 1) Full diff: https://github.com/llvm/llvm-project/pull/120916.diff 2 Files Affected:
diff --git a/llvm/lib/Analysis/Loads.cpp b/llvm/lib/Analysis/Loads.cpp
index 54b9521fda8fd2..c56a45aa32ae6f 100644
--- a/llvm/lib/Analysis/Loads.cpp
+++ b/llvm/lib/Analysis/Loads.cpp
@@ -173,9 +173,11 @@ static bool isDereferenceableAndAlignedPointer(
if (CtxI) {
/// Look through assumes to see if both dereferencability and alignment can
- /// be provent by an assume
+ /// be provent by an assume if needed.
RetainedKnowledge AlignRK;
RetainedKnowledge DerefRK;
+ APInt Offset(DL.getTypeStoreSizeInBits(V->getType()), 0);
+ bool IsAligned = isAligned(V, Offset, Alignment, DL);
if (getKnowledgeForValue(
V, {Attribute::Dereferenceable, Attribute::Alignment}, AC,
[&](RetainedKnowledge RK, Instruction *Assume, auto) {
@@ -185,8 +187,10 @@ static bool isDereferenceableAndAlignedPointer(
AlignRK = std::max(AlignRK, RK);
if (RK.AttrKind == Attribute::Dereferenceable)
DerefRK = std::max(DerefRK, RK);
- if (AlignRK && DerefRK && AlignRK.ArgValue >= Alignment.value() &&
- DerefRK.ArgValue >= Size.getZExtValue())
+ if (!IsAligned && AlignRK &&
+ AlignRK.ArgValue >= Alignment.value())
+ return false;
+ if (DerefRK && DerefRK.ArgValue >= Size.getZExtValue())
return true; // We have found what we needed so we stop looking
return false; // Other assumes may have better information. so
// keep looking
diff --git a/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll b/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll
index 8baff7b33118bf..6eee3be683580a 100644
--- a/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll
+++ b/llvm/test/Transforms/LoopVectorize/dereferenceable-info-from-assumption-constant-size.ll
@@ -822,32 +822,15 @@ define void @deref_assumption_in_preheader_constant_trip_count_align_1(ptr noali
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
-; CHECK-NEXT: [[TMP4:%.*]] = xor <2 x i1> [[TMP3]], splat (i1 true)
-; CHECK-NEXT: [[TMP5:%.*]] = extractelement <2 x i1> [[TMP4]], i32 0
-; CHECK-NEXT: br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
-; CHECK: [[PRED_LOAD_IF]]:
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP0]]
-; CHECK-NEXT: [[TMP7:%.*]] = load i32, ptr [[TMP6]], align 1
-; CHECK-NEXT: [[TMP8:%.*]] = insertelement <2 x i32> poison, i32 [[TMP7]], i32 0
-; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE]]
-; CHECK: [[PRED_LOAD_CONTINUE]]:
-; CHECK-NEXT: [[TMP9:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP8]], %[[PRED_LOAD_IF]] ]
-; CHECK-NEXT: [[TMP10:%.*]] = extractelement <2 x i1> [[TMP4]], i32 1
-; CHECK-NEXT: br i1 [[TMP10]], label %[[PRED_LOAD_IF1:.*]], label %[[PRED_LOAD_CONTINUE2]]
-; CHECK: [[PRED_LOAD_IF1]]:
-; CHECK-NEXT: [[TMP11:%.*]] = add i64 [[INDEX]], 1
-; CHECK-NEXT: [[TMP12:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP11]]
-; CHECK-NEXT: [[TMP13:%.*]] = load i32, ptr [[TMP12]], align 1
-; CHECK-NEXT: [[TMP14:%.*]] = insertelement <2 x i32> [[TMP9]], i32 [[TMP13]], i32 1
-; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE2]]
-; CHECK: [[PRED_LOAD_CONTINUE2]]:
-; CHECK-NEXT: [[TMP15:%.*]] = phi <2 x i32> [ [[TMP9]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP14]], %[[PRED_LOAD_IF1]] ]
+; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i32, ptr [[TMP6]], i32 0
+; CHECK-NEXT: [[TMP15:%.*]] = load <2 x i32>, ptr [[TMP5]], align 1
; CHECK-NEXT: [[PREDPHI:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> [[WIDE_LOAD]], <2 x i32> [[TMP15]]
; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP17:%.*]] = getelementptr inbounds i32, ptr [[TMP16]], i32 0
@@ -1012,15 +995,32 @@ define void @align_and_deref_assumption_in_preheader_constant_trip_count_align_4
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
+; CHECK-NEXT: [[TMP15:%.*]] = xor <2 x i1> [[TMP3]], splat (i1 true)
+; CHECK-NEXT: [[TMP5:%.*]] = extractelement <2 x i1> [[TMP15]], i32 0
+; CHECK-NEXT: br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
+; CHECK: [[PRED_LOAD_IF]]:
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP0]]
-; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i32, ptr [[TMP4]], i32 0
-; CHECK-NEXT: [[WIDE_LOAD1:%.*]] = load <2 x i32>, ptr [[TMP5]], align 4
+; CHECK-NEXT: [[TMP16:%.*]] = load i32, ptr [[TMP4]], align 4
+; CHECK-NEXT: [[TMP17:%.*]] = insertelement <2 x i32> poison, i32 [[TMP16]], i32 0
+; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE]]
+; CHECK: [[PRED_LOAD_CONTINUE]]:
+; CHECK-NEXT: [[TMP9:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP17]], %[[PRED_LOAD_IF]] ]
+; CHECK-NEXT: [[TMP10:%.*]] = extractelement <2 x i1> [[TMP15]], i32 1
+; CHECK-NEXT: br i1 [[TMP10]], label %[[PRED_LOAD_IF1:.*]], label %[[PRED_LOAD_CONTINUE2]]
+; CHECK: [[PRED_LOAD_IF1]]:
+; CHECK-NEXT: [[TMP11:%.*]] = add i64 [[INDEX]], 1
+; CHECK-NEXT: [[TMP12:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP11]]
+; CHECK-NEXT: [[TMP13:%.*]] = load i32, ptr [[TMP12]], align 4
+; CHECK-NEXT: [[TMP14:%.*]] = insertelement <2 x i32> [[TMP9]], i32 [[TMP13]], i32 1
+; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE2]]
+; CHECK: [[PRED_LOAD_CONTINUE2]]:
+; CHECK-NEXT: [[WIDE_LOAD1:%.*]] = phi <2 x i32> [ [[TMP9]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP14]], %[[PRED_LOAD_IF1]] ]
; CHECK-NEXT: [[PREDPHI:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> [[WIDE_LOAD]], <2 x i32> [[WIDE_LOAD1]]
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP7:%.*]] = getelementptr inbounds i32, ptr [[TMP6]], i32 0
@@ -1091,32 +1091,15 @@ define void @deref_assumption_in_preheader_constant_trip_count_align_4_known_via
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
-; CHECK-NEXT: [[TMP4:%.*]] = xor <2 x i1> [[TMP3]], splat (i1 true)
-; CHECK-NEXT: [[TMP5:%.*]] = extractelement <2 x i1> [[TMP4]], i32 0
-; CHECK-NEXT: br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
-; CHECK: [[PRED_LOAD_IF]]:
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP0]]
-; CHECK-NEXT: [[TMP7:%.*]] = load i32, ptr [[TMP6]], align 4
-; CHECK-NEXT: [[TMP8:%.*]] = insertelement <2 x i32> poison, i32 [[TMP7]], i32 0
-; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE]]
-; CHECK: [[PRED_LOAD_CONTINUE]]:
-; CHECK-NEXT: [[TMP9:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP8]], %[[PRED_LOAD_IF]] ]
-; CHECK-NEXT: [[TMP10:%.*]] = extractelement <2 x i1> [[TMP4]], i32 1
-; CHECK-NEXT: br i1 [[TMP10]], label %[[PRED_LOAD_IF1:.*]], label %[[PRED_LOAD_CONTINUE2]]
-; CHECK: [[PRED_LOAD_IF1]]:
-; CHECK-NEXT: [[TMP11:%.*]] = add i64 [[INDEX]], 1
-; CHECK-NEXT: [[TMP12:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP11]]
-; CHECK-NEXT: [[TMP13:%.*]] = load i32, ptr [[TMP12]], align 4
-; CHECK-NEXT: [[TMP14:%.*]] = insertelement <2 x i32> [[TMP9]], i32 [[TMP13]], i32 1
-; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE2]]
-; CHECK: [[PRED_LOAD_CONTINUE2]]:
-; CHECK-NEXT: [[TMP15:%.*]] = phi <2 x i32> [ [[TMP9]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP14]], %[[PRED_LOAD_IF1]] ]
+; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i32, ptr [[TMP6]], i32 0
+; CHECK-NEXT: [[TMP15:%.*]] = load <2 x i32>, ptr [[TMP5]], align 4
; CHECK-NEXT: [[PREDPHI:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> [[WIDE_LOAD]], <2 x i32> [[TMP15]]
; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP17:%.*]] = getelementptr inbounds i32, ptr [[TMP16]], i32 0
@@ -1186,32 +1169,15 @@ define void @deref_assumption_in_preheader_constant_trip_count_align_4_not_known
; CHECK: [[VECTOR_PH]]:
; CHECK-NEXT: br label %[[VECTOR_BODY:.*]]
; CHECK: [[VECTOR_BODY]]:
-; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[PRED_LOAD_CONTINUE2:.*]] ]
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP2:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i32 0
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <2 x i32>, ptr [[TMP2]], align 4
; CHECK-NEXT: [[TMP3:%.*]] = icmp sge <2 x i32> [[WIDE_LOAD]], zeroinitializer
-; CHECK-NEXT: [[TMP4:%.*]] = xor <2 x i1> [[TMP3]], splat (i1 true)
-; CHECK-NEXT: [[TMP5:%.*]] = extractelement <2 x i1> [[TMP4]], i32 0
-; CHECK-NEXT: br i1 [[TMP5]], label %[[PRED_LOAD_IF:.*]], label %[[PRED_LOAD_CONTINUE:.*]]
-; CHECK: [[PRED_LOAD_IF]]:
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP0]]
-; CHECK-NEXT: [[TMP7:%.*]] = load i32, ptr [[TMP6]], align 4
-; CHECK-NEXT: [[TMP8:%.*]] = insertelement <2 x i32> poison, i32 [[TMP7]], i32 0
-; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE]]
-; CHECK: [[PRED_LOAD_CONTINUE]]:
-; CHECK-NEXT: [[TMP9:%.*]] = phi <2 x i32> [ poison, %[[VECTOR_BODY]] ], [ [[TMP8]], %[[PRED_LOAD_IF]] ]
-; CHECK-NEXT: [[TMP10:%.*]] = extractelement <2 x i1> [[TMP4]], i32 1
-; CHECK-NEXT: br i1 [[TMP10]], label %[[PRED_LOAD_IF1:.*]], label %[[PRED_LOAD_CONTINUE2]]
-; CHECK: [[PRED_LOAD_IF1]]:
-; CHECK-NEXT: [[TMP11:%.*]] = add i64 [[INDEX]], 1
-; CHECK-NEXT: [[TMP12:%.*]] = getelementptr i32, ptr [[A]], i64 [[TMP11]]
-; CHECK-NEXT: [[TMP13:%.*]] = load i32, ptr [[TMP12]], align 4
-; CHECK-NEXT: [[TMP14:%.*]] = insertelement <2 x i32> [[TMP9]], i32 [[TMP13]], i32 1
-; CHECK-NEXT: br label %[[PRED_LOAD_CONTINUE2]]
-; CHECK: [[PRED_LOAD_CONTINUE2]]:
-; CHECK-NEXT: [[TMP15:%.*]] = phi <2 x i32> [ [[TMP9]], %[[PRED_LOAD_CONTINUE]] ], [ [[TMP14]], %[[PRED_LOAD_IF1]] ]
+; CHECK-NEXT: [[TMP5:%.*]] = getelementptr i32, ptr [[TMP6]], i32 0
+; CHECK-NEXT: [[TMP15:%.*]] = load <2 x i32>, ptr [[TMP5]], align 4
; CHECK-NEXT: [[PREDPHI:%.*]] = select <2 x i1> [[TMP3]], <2 x i32> [[WIDE_LOAD]], <2 x i32> [[TMP15]]
; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds i32, ptr [[C]], i64 [[TMP0]]
; CHECK-NEXT: [[TMP17:%.*]] = getelementptr inbounds i32, ptr [[TMP16]], i32 0
|
arsenm
reviewed
Dec 23, 2024
llvm/lib/Analysis/Loads.cpp
Outdated
| @@ -173,9 +173,11 @@ static bool isDereferenceableAndAlignedPointer( | |||
|
|
|||
| if (CtxI) { | |||
| /// Look through assumes to see if both dereferencability and alignment can | |||
| /// be provent by an assume | |||
| /// be provent by an assume if needed. | |||
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| /// be provent by an assume if needed. | |
| /// be proven by an assume if needed. |
llvm/lib/Analysis/Loads.cpp
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| APInt Offset(DL.getTypeStoreSizeInBits(V->getType()), 0); | ||
| bool IsAligned = isAligned(V, Offset, Alignment, DL); |
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Can you just use getPointerAlignment directly? isAligned is just making you use this temporary 0 offset
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FWIW I just dropped the offset argument in a5c3cbf. Though TBH it may make more sense to inline the function.
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ping :) |
Also use isAligned when trying to use alignment and dereferenceable assumptions. This catches cases where dereferencable is known via the assumption but alignment is known via isAligned (e.g. via argument attribute or align of 1)
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…sumptions. (#120916) Also use getPointerAlignment when trying to use alignment and dereferenceable assumptions. This catches cases where dereferencable is known via the assumption but alignment is known via getPointerAlignment (e.g. via argument attribute or align of 1) PR: llvm/llvm-project#120916
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…lvm#120916) Also use getPointerAlignment when trying to use alignment and dereferenceable assumptions. This catches cases where dereferencable is known via the assumption but alignment is known via getPointerAlignment (e.g. via argument attribute or align of 1) PR: llvm#120916
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Also use getPointerAlignment when trying to use alignment and dereferenceable assumptions. This catches cases where dereferencable is known via the assumption but alignment is known via getPointerAlignment (e.g. via argument attribute or align of 1)