[llvm] [X86] Avoid repeated hash lookups (NFC) (PR #130710)

[Kazu Hirata via llvm-commits]

https://github.com/kazutakahirata updated https://github.com/llvm/llvm-project/pull/130710

>From 9a3ef94517784200f33d86e328a68a5409a3e072 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Mon, 10 Mar 2025 10:22:41 -0700
Subject: [PATCH 1/2] [X86] Avoid repeated hash lookups (NFC)

---
 llvm/lib/Target/X86/X86PreTileConfig.cpp | 28 +++++++++++++-----------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/Target/X86/X86PreTileConfig.cpp b/llvm/lib/Target/X86/X86PreTileConfig.cpp
index f2ec4369a5ca4..ebf6438b25c51 100644
--- a/llvm/lib/Target/X86/X86PreTileConfig.cpp
+++ b/llvm/lib/Target/X86/X86PreTileConfig.cpp
@@ -293,29 +293,30 @@ bool X86PreTileConfig::runOnMachineFunction(MachineFunction &MF) {
   SmallVector<MachineBasicBlock *, 8> CfgLiveInBBs;
   for (auto &MBB : MF) {
     size_t Pos = 0;
+    auto &Info = BBVisitedInfo[&MBB];
     for (auto &MI : MBB) {
       ++Pos;
       if (isAMXInstruction(MI)) {
         // If there's call before the AMX, we need to reload tile config.
-        if (BBVisitedInfo[&MBB].LastCall)
-          CfgNeedInsert.insert(BBVisitedInfo[&MBB].LastCall);
+        if (Info.LastCall)
+          CfgNeedInsert.insert(Info.LastCall);
         else // Otherwise, we need tile config to live in this BB.
-          BBVisitedInfo[&MBB].NeedTileCfgLiveIn = true;
+          Info.NeedTileCfgLiveIn = true;
         // Always record the first AMX in case there's shape def after it.
-        if (!BBVisitedInfo[&MBB].FirstAMX)
-          BBVisitedInfo[&MBB].FirstAMX = MIRef(&MI, &MBB, Pos);
+        if (!Info.FirstAMX)
+          Info.FirstAMX = MIRef(&MI, &MBB, Pos);
       } else if (MI.isCall() && isDestructiveCall(MI, AMXRegs)) {
         // Record the call only if the callee clobbers all AMX registers.
-        BBVisitedInfo[&MBB].LastCall = MIRef(&MI, &MBB, Pos);
+        Info.LastCall = MIRef(&MI, &MBB, Pos);
       }
     }
-    if (BBVisitedInfo[&MBB].NeedTileCfgLiveIn) {
+    if (Info.NeedTileCfgLiveIn) {
       if (&MBB == &MF.front())
         CfgNeedInsert.insert(MIRef(&MBB));
       else
         CfgLiveInBBs.push_back(&MBB);
     }
-    if (BBVisitedInfo[&MBB].FirstAMX || BBVisitedInfo[&MBB].HasAMXRegLiveIn)
+    if (Info.FirstAMX || Info.HasAMXRegLiveIn)
       for (auto *Succ : MBB.successors())
         if (!isLoopBackEdge(Succ, &MBB))
           BBVisitedInfo[Succ].HasAMXRegLiveIn = true;
@@ -344,16 +345,16 @@ bool X86PreTileConfig::runOnMachineFunction(MachineFunction &MF) {
   // Avoid to insert ldtilecfg before any shape defs.
   SmallVector<MachineBasicBlock *, 8> WorkList;
   for (auto &I : ShapeBBs) {
+    auto &Info = BBVisitedInfo[I.first];
     // TODO: We can hoist shapes across BBs here.
-    if (BBVisitedInfo[I.first].HasAMXRegLiveIn) {
+    if (Info.HasAMXRegLiveIn) {
       // We are not able to config tile registers since the shape to config
       // is not defined yet. Emit error message and continue. The function
       // would not config tile registers.
       emitErrorMsg(MF);
       return false;
     }
-    if (BBVisitedInfo[I.first].FirstAMX &&
-        BBVisitedInfo[I.first].FirstAMX < I.second.back() &&
+    if (Info.FirstAMX && Info.FirstAMX < I.second.back() &&
         !hoistShapesInBB(I.first, I.second)) {
       emitErrorMsg(MF);
       return false;
@@ -363,8 +364,9 @@ bool X86PreTileConfig::runOnMachineFunction(MachineFunction &MF) {
   while (!WorkList.empty()) {
     MachineBasicBlock *MBB = WorkList.pop_back_val();
     for (auto *Pred : MBB->predecessors()) {
-      if (!BBVisitedInfo[Pred].TileCfgForbidden && !isLoopBackEdge(MBB, Pred)) {
-        BBVisitedInfo[Pred].TileCfgForbidden = true;
+      auto &Info = BBVisitedInfo[Pred];
+      if (!Info.TileCfgForbidden && !isLoopBackEdge(MBB, Pred)) {
+        Info.TileCfgForbidden = true;
         WorkList.push_back(Pred);
       }
     }

>From 82aa6f009b358edbbca333f593c3adfb27bb3863 Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu at google.com>
Date: Tue, 11 Mar 2025 07:52:39 -0700
Subject: [PATCH 2/2] Address a comment.

---
 llvm/lib/Target/X86/X86PreTileConfig.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/X86/X86PreTileConfig.cpp b/llvm/lib/Target/X86/X86PreTileConfig.cpp
index ebf6438b25c51..d176778afef92 100644
--- a/llvm/lib/Target/X86/X86PreTileConfig.cpp
+++ b/llvm/lib/Target/X86/X86PreTileConfig.cpp
@@ -326,10 +326,11 @@ bool X86PreTileConfig::runOnMachineFunction(MachineFunction &MF) {
   while (!CfgLiveInBBs.empty()) {
     MachineBasicBlock *MBB = CfgLiveInBBs.pop_back_val();
     for (auto *Pred : MBB->predecessors()) {
+      auto &Info = BBVisitedInfo[Pred];
       if (BBVisitedInfo[Pred].LastCall) {
-        CfgNeedInsert.insert(BBVisitedInfo[Pred].LastCall);
-      } else if (!BBVisitedInfo[Pred].NeedTileCfgLiveIn) {
-        BBVisitedInfo[Pred].NeedTileCfgLiveIn = true;
+        CfgNeedInsert.insert(Info.LastCall);
+      } else if (!Info.NeedTileCfgLiveIn) {
+        Info.NeedTileCfgLiveIn = true;
         if (Pred == &MF.front())
           CfgNeedInsert.insert(MIRef(Pred));
         else