Greedy: Move physreg check when trying to recolor vregs (NFC)

[arsenm]

Instead of checking if the recoloring candidate is a virtual register,
avoid adding it to the candidates in the first place.

[arsenm]

• Greedy: Use initializer list for recoloring candidates (NFC) #160486
• Greedy: Merge VirtRegMap queries into one use (NFC) #160485
• Greedy: Move physreg check when trying to recolor vregs (NFC) #160484 👈 (View in Graphite)
• RegAllocGreedy: Check if copied lanes are live in trySplitAroundHintReg #160424 : 1 other dependent PR (#160467 )
• Greedy: Make trySplitAroundHintReg try to match hints with subreg copies #160294
• main

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[llvmbot]

@llvm/pr-subscribers-llvm-regalloc

Author: Matt Arsenault (arsenm)

Changes

Instead of checking if the recoloring candidate is a virtual register,
avoid adding it to the candidates in the first place.

---

Full diff: https://github.com/llvm/llvm-project/pull/160484.diff

1 Files Affected:

• (modified) llvm/lib/CodeGen/RegAllocGreedy.cpp (+2-5)

diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 6e0585b2e9e55..dc23ab3ce9d2b 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -2502,10 +2502,6 @@ void RAGreedy::tryHintRecoloring(const LiveInterval &VirtReg) {
   do {
     Reg = RecoloringCandidates.pop_back_val();
 
-    // We cannot recolor physical register.
-    if (Reg.isPhysical())
-      continue;
-
     // This may be a skipped register.
     if (!VRM->hasPhys(Reg)) {
       assert(!shouldAllocateRegister(Reg) &&
@@ -2553,7 +2549,8 @@ void RAGreedy::tryHintRecoloring(const LiveInterval &VirtReg) {
     // Push all copy-related live-ranges to keep reconciling the broken
     // hints.
     for (const HintInfo &HI : Info) {
-      if (Visited.insert(HI.Reg).second)
+      // We cannot recolor physical register.
+      if (HI.Reg.isVirtual() && Visited.insert(HI.Reg).second)
         RecoloringCandidates.push_back(HI.Reg);
     }
   } while (!RecoloringCandidates.empty());

[llvmbot]

@llvm/pr-subscribers-backend-systemz

Author: Matt Arsenault (arsenm)

Changes

Instead of checking if the recoloring candidate is a virtual register,
avoid adding it to the candidates in the first place.

---

Full diff: https://github.com/llvm/llvm-project/pull/160484.diff

1 Files Affected:

• (modified) llvm/lib/CodeGen/RegAllocGreedy.cpp (+2-5)

diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 6e0585b2e9e55..dc23ab3ce9d2b 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -2502,10 +2502,6 @@ void RAGreedy::tryHintRecoloring(const LiveInterval &VirtReg) {
   do {
     Reg = RecoloringCandidates.pop_back_val();
 
-    // We cannot recolor physical register.
-    if (Reg.isPhysical())
-      continue;
-
     // This may be a skipped register.
     if (!VRM->hasPhys(Reg)) {
       assert(!shouldAllocateRegister(Reg) &&
@@ -2553,7 +2549,8 @@ void RAGreedy::tryHintRecoloring(const LiveInterval &VirtReg) {
     // Push all copy-related live-ranges to keep reconciling the broken
     // hints.
     for (const HintInfo &HI : Info) {
-      if (Visited.insert(HI.Reg).second)
+      // We cannot recolor physical register.
+      if (HI.Reg.isVirtual() && Visited.insert(HI.Reg).second)
         RecoloringCandidates.push_back(HI.Reg);
     }
   } while (!RecoloringCandidates.empty());

[llvmbot]

@llvm/pr-subscribers-backend-x86

Author: Matt Arsenault (arsenm)

Changes

Instead of checking if the recoloring candidate is a virtual register,
avoid adding it to the candidates in the first place.

---

Full diff: https://github.com/llvm/llvm-project/pull/160484.diff

1 Files Affected:

• (modified) llvm/lib/CodeGen/RegAllocGreedy.cpp (+2-5)

diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 6e0585b2e9e55..dc23ab3ce9d2b 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -2502,10 +2502,6 @@ void RAGreedy::tryHintRecoloring(const LiveInterval &VirtReg) {
   do {
     Reg = RecoloringCandidates.pop_back_val();
 
-    // We cannot recolor physical register.
-    if (Reg.isPhysical())
-      continue;
-
     // This may be a skipped register.
     if (!VRM->hasPhys(Reg)) {
       assert(!shouldAllocateRegister(Reg) &&
@@ -2553,7 +2549,8 @@ void RAGreedy::tryHintRecoloring(const LiveInterval &VirtReg) {
     // Push all copy-related live-ranges to keep reconciling the broken
     // hints.
     for (const HintInfo &HI : Info) {
-      if (Visited.insert(HI.Reg).second)
+      // We cannot recolor physical register.
+      if (HI.Reg.isVirtual() && Visited.insert(HI.Reg).second)
         RecoloringCandidates.push_back(HI.Reg);
     }
   } while (!RecoloringCandidates.empty());

[preames]

LGTM

[qcolombet]

Good catch!