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[SystemZ] Treat FAKE_USE instructions as instructions without a size #144390

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Merged
merged 1 commit into from
Jun 18, 2025
Merged

[SystemZ] Treat FAKE_USE instructions as instructions without a size #144390

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2 changes: 1 addition & 1 deletion llvm/lib/Target/SystemZ/SystemZLongBranch.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -215,7 +215,7 @@ static unsigned getInstSizeInBytes(const MachineInstr &MI,
// These do not have a size:
MI.isDebugOrPseudoInstr() || MI.isPosition() || MI.isKill() ||
MI.isImplicitDef() || MI.getOpcode() == TargetOpcode::MEMBARRIER ||
MI.getOpcode() == TargetOpcode::INIT_UNDEF ||
MI.getOpcode() == TargetOpcode::INIT_UNDEF || MI.isFakeUse() ||
// These have a size that may be zero:
MI.isInlineAsm() || MI.getOpcode() == SystemZ::STACKMAP ||
MI.getOpcode() == SystemZ::PATCHPOINT ||
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14 changes: 14 additions & 0 deletions llvm/test/CodeGen/SystemZ/fake-use-size.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
; RUN: llc -O0 < %s -mtriple=s390x-linux-gnu 2>&1 | FileCheck %s

;; Tests that we can handle FAKE_USE instructions, emitting a comment for them
;; in the resulting assembly.

; CHECK: .type idd,@function
; CHECK: # %bb.0:
; CHECK-NEXT: # fake_use:

define double @idd(double %d) {
entry:
notail call void (...) @llvm.fake.use(double %d)
ret double %d
}
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