[PATCH] D131932: Do not count identity copies for register allocation costs
Matthias Braun via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 15 17:42:48 PDT 2022
MatzeB created this revision.
MatzeB added reviewers: skatkov, anemet, thegameg, mtrofin.
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We should not count `COPY`s between two virtual registers that end up using the same physical register. They will get removed in the `virtregmap` pass.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D131932
Files:
llvm/lib/CodeGen/RegAllocGreedy.cpp
llvm/test/CodeGen/X86/statepoint-ra.ll
Index: llvm/test/CodeGen/X86/statepoint-ra.ll
===================================================================
--- llvm/test/CodeGen/X86/statepoint-ra.ll
+++ llvm/test/CodeGen/X86/statepoint-ra.ll
@@ -20,10 +20,6 @@
;YAML: - String: ' total reloads cost '
;YAML: - NumZeroCostFoldedReloads: '20'
;YAML: - String: ' zero cost folded reloads '
-;YAML: - NumVRCopies: '2'
-;YAML: - String: ' virtual registers copies '
-;YAML: - TotalCopiesCost: '8.882868e-16'
-;YAML: - String: ' total copies cost '
;YAML: - String: generated in function
define void @barney(ptr addrspace(1) %arg, double %arg1, double %arg2, double %arg3, double %arg4, double %arg5, double %arg6, double %arg7, double %arg8, double %arg9, double %arg10, double %arg11, double %arg12) gc "statepoint-example" personality ptr @widget {
Index: llvm/lib/CodeGen/RegAllocGreedy.cpp
===================================================================
--- llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -2372,8 +2372,16 @@
MachineOperand &Dest = MI.getOperand(0);
MachineOperand &Src = MI.getOperand(1);
if (Dest.isReg() && Src.isReg() && Dest.getReg().isVirtual() &&
- Src.getReg().isVirtual())
- ++Stats.Copies;
+ Src.getReg().isVirtual()) {
+ MCRegister SrcReg = VRM->getPhys(Src.getReg());
+ if (Src.getSubReg())
+ SrcReg = TRI->getSubReg(SrcReg, Src.getSubReg());
+ MCRegister DestReg = VRM->getPhys(Dest.getReg());
+ if (Dest.getSubReg())
+ DestReg = TRI->getSubReg(DestReg, Dest.getSubReg());
+ if (SrcReg != DestReg)
+ ++Stats.Copies;
+ }
continue;
}
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