[llvm] [TBAA] Extract logic to use TBAA tag for field of !tbaa.struct (NFC). (PR #81284)

[Florian Hahn via llvm-commits]

https://github.com/fhahn updated https://github.com/llvm/llvm-project/pull/81284

>From e6de9f21b162c57dd09cb4de3147b7ab09ef8681 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Fri, 9 Feb 2024 13:29:19 +0000
Subject: [PATCH 1/2] [TBAA] Extract logic to use TBAA tag for field of
 !tbaa.struct (NFC).

---
 llvm/include/llvm/IR/Metadata.h                   |  5 +++++
 llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp      | 14 ++++++++++++++
 .../Transforms/InstCombine/InstCombineCalls.cpp   | 15 +--------------
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/llvm/include/llvm/IR/Metadata.h b/llvm/include/llvm/IR/Metadata.h
index db1f44fea3b459..6f23ac44dee968 100644
--- a/llvm/include/llvm/IR/Metadata.h
+++ b/llvm/include/llvm/IR/Metadata.h
@@ -844,6 +844,11 @@ struct AAMDNodes {
   /// together. Different from `merge`, where different locations should
   /// overlap each other, `concat` puts non-overlapping locations together.
   AAMDNodes concat(const AAMDNodes &Other) const;
+
+  /// Create a new AAMDNode for accessing \p AccessSize bytes of this AAMDNode.
+  /// If his AAMDNode has !tbaa.struct and \p AccessSize matches the size of the
+  /// field at offset 0, get the TBAA tag describing the accessed field.
+  AAMDNodes adjustForAccess(unsigned AccessSize);
 };
 
 // Specialize DenseMapInfo for AAMDNodes.
diff --git a/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp b/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
index e4dc1a867f6f0c..edc08cde686f1f 100644
--- a/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -817,3 +817,17 @@ MDNode *AAMDNodes::extendToTBAA(MDNode *MD, ssize_t Len) {
       ConstantAsMetadata::get(ConstantInt::get(PreviousSize->getType(), Len));
   return MDNode::get(MD->getContext(), NextNodes);
 }
+
+AAMDNodes AAMDNodes::adjustForAccess(unsigned AccessSize) {
+  AAMDNodes New = *this;
+  MDNode *M = New.TBAAStruct;
+  New.TBAAStruct = nullptr;
+  if (M && M->getNumOperands() == 3 && M->getOperand(0) &&
+      mdconst::hasa<ConstantInt>(M->getOperand(0)) &&
+      mdconst::extract<ConstantInt>(M->getOperand(0))->isZero() &&
+      M->getOperand(1) && mdconst::hasa<ConstantInt>(M->getOperand(1)) &&
+      mdconst::extract<ConstantInt>(M->getOperand(1))->getValue() == AccessSize &&
+      M->getOperand(2) && isa<MDNode>(M->getOperand(2)))
+    New.TBAA = cast<MDNode>(M->getOperand(2));
+  return New;
+}
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index ed5d44757fbeb6..56d1259e955196 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -172,20 +172,7 @@ Instruction *InstCombinerImpl::SimplifyAnyMemTransfer(AnyMemTransferInst *MI) {
 
   // If the memcpy has metadata describing the members, see if we can get the
   // TBAA tag describing our copy.
-  AAMDNodes AACopyMD = MI->getAAMetadata();
-
-  if (MDNode *M = AACopyMD.TBAAStruct) {
-    AACopyMD.TBAAStruct = nullptr;
-    if (M->getNumOperands() == 3 && M->getOperand(0) &&
-        mdconst::hasa<ConstantInt>(M->getOperand(0)) &&
-        mdconst::extract<ConstantInt>(M->getOperand(0))->isZero() &&
-        M->getOperand(1) &&
-        mdconst::hasa<ConstantInt>(M->getOperand(1)) &&
-        mdconst::extract<ConstantInt>(M->getOperand(1))->getValue() ==
-        Size &&
-        M->getOperand(2) && isa<MDNode>(M->getOperand(2)))
-      AACopyMD.TBAA = cast<MDNode>(M->getOperand(2));
-  }
+  AAMDNodes AACopyMD = MI->getAAMetadata().adjustForAccess(Size);
 
   Value *Src = MI->getArgOperand(1);
   Value *Dest = MI->getArgOperand(0);

>From 96a983cdb8d37aea07ca3aaa437ec79521669c91 Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Mon, 12 Feb 2024 09:38:27 +0000
Subject: [PATCH 2/2] !fixup fix formatting.

---
 llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp b/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
index edc08cde686f1f..d05f42552e81de 100644
--- a/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/TypeBasedAliasAnalysis.cpp
@@ -826,7 +826,8 @@ AAMDNodes AAMDNodes::adjustForAccess(unsigned AccessSize) {
       mdconst::hasa<ConstantInt>(M->getOperand(0)) &&
       mdconst::extract<ConstantInt>(M->getOperand(0))->isZero() &&
       M->getOperand(1) && mdconst::hasa<ConstantInt>(M->getOperand(1)) &&
-      mdconst::extract<ConstantInt>(M->getOperand(1))->getValue() == AccessSize &&
+      mdconst::extract<ConstantInt>(M->getOperand(1))->getValue() ==
+          AccessSize &&
       M->getOperand(2) && isa<MDNode>(M->getOperand(2)))
     New.TBAA = cast<MDNode>(M->getOperand(2));
   return New;