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[RISCV] Fix stackmap shadow trimming NOP size for compressed targets (#189774)

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The shadow trimming loop in LowerSTACKMAP hardcoded a 4-byte decrement
per instruction, but when Zca is enabled NOPs are 2 bytes. Use NOPBytes
instead of the hardcoded 4 so the shadow is correctly trimmed on
compressed targets.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Jim Lin 2026-04-02 08:21:33 +08:00 committed by GitHub
parent b9e01c26f0
commit 3d7eedce56
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GPG Key ID: B5690EEEBB952194
2 changed files with 15 additions and 3 deletions
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2
llvm/lib/Target/RISCV/RISCVAsmPrinter.cpp
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@ -155,7 +155,7 @@ void RISCVAsmPrinter::LowerSTACKMAP(MCStreamer &OutStreamer, StackMaps &SM,
MII->getOpcode() == TargetOpcode::STACKMAP)
break;
++MII;
NumNOPBytes -= 4;
NumNOPBytes -= NOPBytes;
}
// Emit nops.

16
llvm/test/CodeGen/RISCV/rv64-stackmap-nops.ll
View File

@ -1,5 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=riscv64 | FileCheck %s
; RUN: llc < %s -mtriple=riscv64 | FileCheck %s --check-prefix=CHECK
; RUN: llc < %s -mtriple=riscv64 -mattr=+c | FileCheck %s --check-prefix=RVC
define void @test_shadow_optimization() {
; CHECK-LABEL: test_shadow_optimization:
@ -9,8 +10,19 @@ define void @test_shadow_optimization() {
; CHECK-NEXT: nop
; CHECK-NEXT: nop
; CHECK-NEXT: ret
;
; RVC-LABEL: test_shadow_optimization:
; RVC: # %bb.0: # %entry
; RVC-NEXT: .Ltmp0:
; RVC-NEXT: nop
; RVC-NEXT: nop
; RVC-NEXT: nop
; RVC-NEXT: nop
; RVC-NEXT: nop
; RVC-NEXT: nop
; RVC-NEXT: nop
; RVC-NEXT: ret
entry:
tail call void (i64, i32, ...) @llvm.experimental.stackmap(i64 0, i32 16)
ret void
}