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Move RBM_SAVED_LOCALLOC_SP reservation from compCompile to setFrameType in LSRA #121745

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Move RBM_SAVED_LOCALLOC_SP reservation from compCompile to setFrameType in LSRA #121745

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8bc4f3b
Initial plan
Copilot Nov 18, 2025
4bab6be
Move RBM_SAVED_LOCALLOC_SP code from compCompile to setFrameType in LSRA
Copilot Nov 18, 2025
8da758e
Add JITDUMP for RBM_SAVED_LOCALLOC_SP reservation
Copilot Nov 18, 2025
b5be711
Update src/coreclr/jit/lsra.cpp
jakobbotsch Nov 18, 2025
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8 changes: 0 additions & 8 deletions src/coreclr/jit/compiler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4950,14 +4950,6 @@ void Compiler::compCompile(void** methodCodePtr, uint32_t* methodCodeSize, JitFl
// call and register argument info, flowgraph and loop info, etc.
compJitStats();

#ifdef TARGET_ARM
if (compLocallocUsed)
{
// We reserve REG_SAVED_LOCALLOC_SP to store SP on entry for stack unwinding
codeGen->regSet.rsMaskResvd |= RBM_SAVED_LOCALLOC_SP;
}
#endif // TARGET_ARM

if (compIsAsync())
{
DoPhase(this, PHASE_ASYNC, &Compiler::TransformAsync);
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10 changes: 10 additions & 0 deletions src/coreclr/jit/lsra.cpp
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Expand Up @@ -2717,6 +2717,16 @@ void LinearScan::setFrameType()
}
#endif // TARGET_ARMARCH || TARGET_RISCV64

#ifdef TARGET_ARM
if (compiler->compLocallocUsed)
{
// We reserve REG_SAVED_LOCALLOC_SP to store SP on entry for stack unwinding
compiler->codeGen->regSet.rsMaskResvd |= RBM_SAVED_LOCALLOC_SP;
Comment on lines +2723 to +2724
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@jakobbotsch jakobbotsch Nov 18, 2025

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Can you add a JITDUMP like the one above about the fact that we are reserving this register?

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@jakobbotsch jakobbotsch Nov 18, 2025

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@copilot Can you add a JITDUMP like the one above about the fact that we are reserving this register?

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Copilot AI Nov 18, 2025

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Added in 8da758e

JITDUMP(" Reserved REG_SAVED_LOCALLOC_SP (%s) due to localloc\n", getRegName(REG_SAVED_LOCALLOC_SP));
removeMask |= RBM_SAVED_LOCALLOC_SP.GetIntRegSet();
}
#endif // TARGET_ARM

if ((removeMask != RBM_NONE) && ((availableIntRegs & removeMask) != 0))
{
// We know that we're already in "read mode" for availableIntRegs. However,
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