[llvm] DAG: Fix constructing a temporary TargetTransformInfo instance (PR #168480)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/168480

TTI is managed by the pass manager, and should use the pre-existing
analysis result. Also fixes some noise where we were only conditionally
querying TTI.

>From 6ab69ce66dbe4d6fe5b42ccb5acb269b1556af65 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Mon, 17 Nov 2025 14:03:40 -0800
Subject: [PATCH] DAG: Fix constructing a temporary TargetTransformInfo
 instance

TTI is managed by the pass manager, and should use the pre-existing
analysis result. Also fixes some noise where we were only conditionally
querying TTI.
---
 llvm/include/llvm/CodeGen/SelectionDAGISel.h          | 4 +---
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 5 +++--
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h   | 3 ++-
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp    | 6 +-----
 4 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/SelectionDAGISel.h b/llvm/include/llvm/CodeGen/SelectionDAGISel.h
index 27acc83369f02..c5cdf76f4777e 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAGISel.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGISel.h
@@ -58,9 +58,7 @@ class SelectionDAGISel {
   AssumptionCache *AC = nullptr;
   GCFunctionInfo *GFI = nullptr;
   SSPLayoutInfo *SP = nullptr;
-#if !defined(NDEBUG) && LLVM_ENABLE_ABI_BREAKING_CHECKS
-  TargetTransformInfo *TTI = nullptr;
-#endif
+  const TargetTransformInfo *TTI = nullptr;
   CodeGenOptLevel OptLevel;
   const TargetInstrInfo *TII;
   const TargetLowering *TLI;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 4f13f3b128ea4..96a2923103ea7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1097,14 +1097,15 @@ RegsForValue::getRegsAndSizes() const {
 }
 
 void SelectionDAGBuilder::init(GCFunctionInfo *gfi, BatchAAResults *aa,
-                               AssumptionCache *ac,
-                               const TargetLibraryInfo *li) {
+                               AssumptionCache *ac, const TargetLibraryInfo *li,
+                               const TargetTransformInfo &TTI) {
   BatchAA = aa;
   AC = ac;
   GFI = gfi;
   LibInfo = li;
   Context = DAG.getContext();
   LPadToCallSiteMap.clear();
+  this->TTI = &TTI;
   SL->init(DAG.getTargetLoweringInfo(), TM, DAG.getDataLayout());
   AssignmentTrackingEnabled = isAssignmentTrackingEnabled(
       *DAG.getMachineFunction().getFunction().getParent());
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 13e2daa783147..d2f720df61e72 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -232,6 +232,7 @@ class SelectionDAGBuilder {
   BatchAAResults *BatchAA = nullptr;
   AssumptionCache *AC = nullptr;
   const TargetLibraryInfo *LibInfo = nullptr;
+  const TargetTransformInfo *TTI = nullptr;
 
   class SDAGSwitchLowering : public SwitchCG::SwitchLowering {
   public:
@@ -285,7 +286,7 @@ class SelectionDAGBuilder {
         FuncInfo(funcinfo), SwiftError(swifterror) {}
 
   void init(GCFunctionInfo *gfi, BatchAAResults *BatchAA, AssumptionCache *AC,
-            const TargetLibraryInfo *li);
+            const TargetLibraryInfo *li, const TargetTransformInfo &TTI);
 
   /// Clear out the current SelectionDAG and the associated state and prepare
   /// this SelectionDAGBuilder object to be used for a new block. This doesn't
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 5bed32db528d6..0fad4722b1871 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -519,9 +519,7 @@ void SelectionDAGISel::initializeAnalysisResults(
 
   SP = &FAM.getResult<SSPLayoutAnalysis>(Fn);
 
-#if !defined(NDEBUG) && LLVM_ENABLE_ABI_BREAKING_CHECKS
   TTI = &FAM.getResult<TargetIRAnalysis>(Fn);
-#endif
 }
 
 void SelectionDAGISel::initializeAnalysisResults(MachineFunctionPass &MFP) {
@@ -578,9 +576,7 @@ void SelectionDAGISel::initializeAnalysisResults(MachineFunctionPass &MFP) {
 
   SP = &MFP.getAnalysis<StackProtector>().getLayoutInfo();
 
-#if !defined(NDEBUG) && LLVM_ENABLE_ABI_BREAKING_CHECKS
   TTI = &MFP.getAnalysis<TargetTransformInfoWrapperPass>().getTTI(Fn);
-#endif
 }
 
 bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
@@ -593,7 +589,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
 
   ISEL_DUMP(dbgs() << "\n\n\n=== " << FuncName << '\n');
 
-  SDB->init(GFI, getBatchAA(), AC, LibInfo);
+  SDB->init(GFI, getBatchAA(), AC, LibInfo, *TTI);
 
   MF->setHasInlineAsm(false);