[llvm] [InstCombine] Propagate invariant.load metadata across unpacked loads (PR #152186)
Vedant Paranjape via llvm-commits
llvm-commits at lists.llvm.org
Wed Aug 13 15:42:45 PDT 2025
https://github.com/VedantParanjape updated https://github.com/llvm/llvm-project/pull/152186
>From a3d0e64801b72f84e73fde09eb037535106a86fb Mon Sep 17 00:00:00 2001
From: Vedant Paranjape <vedantvinaya at nvidia.com>
Date: Tue, 5 Aug 2025 00:04:44 +0000
Subject: [PATCH 1/5] [InstCombine] Propagate invariant.load metadata across
unpacked loads
For loads that operate on aggregate type, instcombine unpacks the
loads. It does not preserve the invariant.load metadata. This patch
fixes that, it looks for the metadata in the parent load and attaches
the metadata to the unpacked loads.
---
.../InstCombineLoadStoreAlloca.cpp | 10 ++++
.../invariant-metadata-propagation.ll | 46 +++++++++++++++++++
2 files changed, 56 insertions(+)
create mode 100644 llvm/test/Transforms/InstCombine/invariant-metadata-propagation.ll
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 0be1034b046b6..68252b06e3a9a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -718,6 +718,14 @@ static Instruction *combineLoadToOperationType(InstCombinerImpl &IC,
return nullptr;
}
+// Check if the aggregate load has a invariant.load metadata
+// If aggregate load has invariant.load metadata, add it to the
+// unpacked loads as well.
+static void copyInvariantLoadMetadata(LoadInst &LI, LoadInst *NewLoad) {
+ if (MDNode *MD = LI.getMetadata("invariant.load"))
+ NewLoad->setMetadata("invariant.load", MD);
+}
+
static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
// FIXME: We could probably with some care handle both volatile and atomic
// stores here but it isn't clear that this is important.
@@ -737,6 +745,7 @@ static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
LoadInst *NewLoad = IC.combineLoadToNewType(LI, ST->getTypeAtIndex(0U),
".unpack");
NewLoad->setAAMetadata(LI.getAAMetadata());
+ copyInvariantLoadMetadata(LI, NewLoad);
return IC.replaceInstUsesWith(LI, IC.Builder.CreateInsertValue(
PoisonValue::get(T), NewLoad, 0, Name));
}
@@ -764,6 +773,7 @@ static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
Name + ".unpack");
// Propagate AA metadata. It'll still be valid on the narrowed load.
L->setAAMetadata(LI.getAAMetadata());
+ copyInvariantLoadMetadata(LI, L);
V = IC.Builder.CreateInsertValue(V, L, i);
}
diff --git a/llvm/test/Transforms/InstCombine/invariant-metadata-propagation.ll b/llvm/test/Transforms/InstCombine/invariant-metadata-propagation.ll
new file mode 100644
index 0000000000000..acc5e7ca8d2b4
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/invariant-metadata-propagation.ll
@@ -0,0 +1,46 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -S < %s -passes=instcombine | FileCheck %s
+
+%struct.double2 = type { double, double }
+%struct.double1 = type { double }
+
+define %struct.double2 @func1(ptr addrspace(1) %a) {
+; CHECK-LABEL: define %struct.double2 @func1(
+; CHECK-SAME: ptr addrspace(1) [[A:%.*]]) {
+; CHECK-NEXT: [[DOTUNPACK:%.*]] = load double, ptr addrspace(1) [[A]], align 16, !invariant.load [[META0:![0-9]+]]
+; CHECK-NEXT: [[TMP1:%.*]] = insertvalue [[STRUCT_DOUBLE2:%.*]] poison, double [[DOTUNPACK]], 0
+; CHECK-NEXT: [[DOTELT1:%.*]] = getelementptr inbounds nuw i8, ptr addrspace(1) [[A]], i64 8
+; CHECK-NEXT: [[DOTUNPACK2:%.*]] = load double, ptr addrspace(1) [[DOTELT1]], align 8, !invariant.load [[META0]]
+; CHECK-NEXT: [[TMP2:%.*]] = insertvalue [[STRUCT_DOUBLE2]] [[TMP1]], double [[DOTUNPACK2]], 1
+; CHECK-NEXT: ret [[STRUCT_DOUBLE2]] [[TMP2]]
+;
+ %1 = load %struct.double2, ptr addrspace(1) %a, align 16, !invariant.load !1
+ ret %struct.double2 %1
+}
+
+define %struct.double2 @func2(ptr %a) {
+; CHECK-LABEL: define %struct.double2 @func2(
+; CHECK-SAME: ptr [[A:%.*]]) {
+; CHECK-NEXT: [[DOTUNPACK:%.*]] = load double, ptr [[A]], align 16, !invariant.load [[META0]]
+; CHECK-NEXT: [[TMP1:%.*]] = insertvalue [[STRUCT_DOUBLE2:%.*]] poison, double [[DOTUNPACK]], 0
+; CHECK-NEXT: [[DOTELT1:%.*]] = getelementptr inbounds nuw i8, ptr [[A]], i64 8
+; CHECK-NEXT: [[DOTUNPACK2:%.*]] = load double, ptr [[DOTELT1]], align 8, !invariant.load [[META0]]
+; CHECK-NEXT: [[TMP2:%.*]] = insertvalue [[STRUCT_DOUBLE2]] [[TMP1]], double [[DOTUNPACK2]], 1
+; CHECK-NEXT: ret [[STRUCT_DOUBLE2]] [[TMP2]]
+;
+ %1 = load %struct.double2, ptr %a, align 16, !invariant.load !1
+ ret %struct.double2 %1
+}
+
+define %struct.double1 @func3(ptr %a) {
+; CHECK-LABEL: define %struct.double1 @func3(
+; CHECK-SAME: ptr [[A:%.*]]) {
+; CHECK-NEXT: [[DOTUNPACK:%.*]] = load double, ptr [[A]], align 16, !invariant.load [[META0]]
+; CHECK-NEXT: [[TMP1:%.*]] = insertvalue [[STRUCT_DOUBLE1:%.*]] poison, double [[DOTUNPACK]], 0
+; CHECK-NEXT: ret [[STRUCT_DOUBLE1]] [[TMP1]]
+;
+ %1 = load %struct.double1, ptr %a, align 16, !invariant.load !1
+ ret %struct.double1 %1
+}
+
+!1 = !{}
>From 71d9921667ea8e7320544ad92d063f0f26dfc740 Mon Sep 17 00:00:00 2001
From: Vedant Paranjape <vedantvinaya at nvidia.com>
Date: Wed, 6 Aug 2025 00:57:24 +0000
Subject: [PATCH 2/5] use enums in mdnode
---
.../lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 68252b06e3a9a..c68eb0bb3568c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -722,8 +722,8 @@ static Instruction *combineLoadToOperationType(InstCombinerImpl &IC,
// If aggregate load has invariant.load metadata, add it to the
// unpacked loads as well.
static void copyInvariantLoadMetadata(LoadInst &LI, LoadInst *NewLoad) {
- if (MDNode *MD = LI.getMetadata("invariant.load"))
- NewLoad->setMetadata("invariant.load", MD);
+ if (MDNode *MD = LI.getMetadata(LLVMContext::MD_invariant_load))
+ NewLoad->setMetadata(LLVMContext::MD_invariant_load, MD);
}
static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
>From 9899e69910fcd2ee482f47d6e458cb4cab90a486 Mon Sep 17 00:00:00 2001
From: Vedant Paranjape <vedantvinaya at nvidia.com>
Date: Wed, 6 Aug 2025 23:06:05 +0000
Subject: [PATCH 3/5] adjust AAMetadata
---
.../Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index c68eb0bb3568c..c9a8ccfe5bbd4 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -771,8 +771,12 @@ static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
ST->getElementType(i), Ptr,
commonAlignment(Align, SL->getElementOffset(i).getKnownMinValue()),
Name + ".unpack");
+ // Adjust AA metadata to new offset and size.
+ AAMDNodes adjustedAANodes = LI.getAAMetadata().adjustForAccess(
+ SL->getElementOffset(i),
+ SL->getElementOffset(i).getKnownMinValue());
// Propagate AA metadata. It'll still be valid on the narrowed load.
- L->setAAMetadata(LI.getAAMetadata());
+ L->setAAMetadata(adjustedAANodes);
copyInvariantLoadMetadata(LI, L);
V = IC.Builder.CreateInsertValue(V, L, i);
}
>From 9955d7094c82599508ca53033613770da5db5868 Mon Sep 17 00:00:00 2001
From: Vedant Paranjape <vedantvinaya at nvidia.com>
Date: Wed, 13 Aug 2025 22:35:53 +0000
Subject: [PATCH 4/5] Revert "adjust AAMetadata"
This reverts commit 9899e69910fcd2ee482f47d6e458cb4cab90a486.
---
.../Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index c9a8ccfe5bbd4..c68eb0bb3568c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -771,12 +771,8 @@ static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
ST->getElementType(i), Ptr,
commonAlignment(Align, SL->getElementOffset(i).getKnownMinValue()),
Name + ".unpack");
- // Adjust AA metadata to new offset and size.
- AAMDNodes adjustedAANodes = LI.getAAMetadata().adjustForAccess(
- SL->getElementOffset(i),
- SL->getElementOffset(i).getKnownMinValue());
// Propagate AA metadata. It'll still be valid on the narrowed load.
- L->setAAMetadata(adjustedAANodes);
+ L->setAAMetadata(LI.getAAMetadata());
copyInvariantLoadMetadata(LI, L);
V = IC.Builder.CreateInsertValue(V, L, i);
}
>From 2d4e276430a30dbd008633b0fe634ad43da11a03 Mon Sep 17 00:00:00 2001
From: Vedant Paranjape <vedantvinaya at nvidia.com>
Date: Wed, 13 Aug 2025 22:37:55 +0000
Subject: [PATCH 5/5] addressed review
---
.../InstCombine/InstCombineLoadStoreAlloca.cpp | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index c68eb0bb3568c..4b10586616c29 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -718,14 +718,6 @@ static Instruction *combineLoadToOperationType(InstCombinerImpl &IC,
return nullptr;
}
-// Check if the aggregate load has a invariant.load metadata
-// If aggregate load has invariant.load metadata, add it to the
-// unpacked loads as well.
-static void copyInvariantLoadMetadata(LoadInst &LI, LoadInst *NewLoad) {
- if (MDNode *MD = LI.getMetadata(LLVMContext::MD_invariant_load))
- NewLoad->setMetadata(LLVMContext::MD_invariant_load, MD);
-}
-
static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
// FIXME: We could probably with some care handle both volatile and atomic
// stores here but it isn't clear that this is important.
@@ -745,7 +737,8 @@ static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
LoadInst *NewLoad = IC.combineLoadToNewType(LI, ST->getTypeAtIndex(0U),
".unpack");
NewLoad->setAAMetadata(LI.getAAMetadata());
- copyInvariantLoadMetadata(LI, NewLoad);
+ // Copy invariant metadata from parent load.
+ NewLoad->copyMetadata(LI, LLVMContext::MD_invariant_load);
return IC.replaceInstUsesWith(LI, IC.Builder.CreateInsertValue(
PoisonValue::get(T), NewLoad, 0, Name));
}
@@ -773,7 +766,8 @@ static Instruction *unpackLoadToAggregate(InstCombinerImpl &IC, LoadInst &LI) {
Name + ".unpack");
// Propagate AA metadata. It'll still be valid on the narrowed load.
L->setAAMetadata(LI.getAAMetadata());
- copyInvariantLoadMetadata(LI, L);
+ // Copy invariant metadata from parent load.
+ L->copyMetadata(LI, LLVMContext::MD_invariant_load);
V = IC.Builder.CreateInsertValue(V, L, i);
}
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