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Don't rely on 'l'(ell) modifiers to indicate a label reference

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Summary:
It's not necessary to use an 'l'(ell) modifier when referencing a label.
Treat block addresses and MBB references as if the modifier is used
anyway. This prevents us from generating references to ficticious
labels.

Reviewers: jyknight, nickdesaulniers, hfinkel

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D71849
This commit is contained in:
Bill Wendling 2019-12-23 16:57:41 -08:00
parent d8fd92eaaa
commit 83d690a149
2 changed files with 45 additions and 20 deletions
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35
llvm/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
View File

@ -456,26 +456,23 @@ static void EmitGCCInlineAsmStr(const char *AsmStr, const MachineInstr *MI,
// FIXME: Shouldn't arch-independent output template handling go into
// PrintAsmOperand?
if (Modifier[0] == 'l') { // Labels are target independent.
if (MI->getOperand(OpNo).isBlockAddress()) {
const BlockAddress *BA = MI->getOperand(OpNo).getBlockAddress();
MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
Sym->print(OS, AP->MAI);
MMI->getContext().registerInlineAsmLabel(Sym);
} else if (MI->getOperand(OpNo).isMBB()) {
const MCSymbol *Sym = MI->getOperand(OpNo).getMBB()->getSymbol();
Sym->print(OS, AP->MAI);
} else {
Error = true;
}
// Labels are target independent.
if (MI->getOperand(OpNo).isBlockAddress()) {
const BlockAddress *BA = MI->getOperand(OpNo).getBlockAddress();
MCSymbol *Sym = AP->GetBlockAddressSymbol(BA);
Sym->print(OS, AP->MAI);
MMI->getContext().registerInlineAsmLabel(Sym);
} else if (MI->getOperand(OpNo).isMBB()) {
const MCSymbol *Sym = MI->getOperand(OpNo).getMBB()->getSymbol();
Sym->print(OS, AP->MAI);
} else if (Modifier[0] == 'l') {
Error = true;
} else if (InlineAsm::isMemKind(OpFlags)) {
Error = AP->PrintAsmMemoryOperand(
MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
} else {
if (InlineAsm::isMemKind(OpFlags)) {
Error = AP->PrintAsmMemoryOperand(
MI, OpNo, Modifier[0] ? Modifier : nullptr, OS);
} else {
Error = AP->PrintAsmOperand(MI, OpNo,
Modifier[0] ? Modifier : nullptr, OS);
}
Error = AP->PrintAsmOperand(MI, OpNo,
Modifier[0] ? Modifier : nullptr, OS);
}
}
if (Error) {

30
llvm/test/CodeGen/X86/callbr-asm.ll
View File

@ -53,7 +53,6 @@ fail:
ret i32 1
}
; Test 3 - asm-goto implements a loop. The loop gets recognized, but many loop
; transforms fail due to canonicalization having callbr exceptions. Trivial
; blocks at labels 1 and 3 also don't get simplified due to callbr.
@ -131,3 +130,32 @@ normal1: ; preds = %normal0
%1 = load i32, i32* %a.addr, align 4
ret i32 %1
}
; Test 4 - asm-goto referenced with the 'l' (ell) modifier and not.
define void @test4() {
; CHECK-LABEL: test4:
; CHECK: # %bb.0:
; CHECK-NEXT: #APP
; CHECK-NOT: ja .Ltmp50
; CHECK-NEXT: ja .Ltmp5
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: .LBB3_1:
; CHECK-NEXT: #APP
; CHECK-NOT: ja .Ltmp50
; CHECK-NEXT: ja .Ltmp5
; CHECK-NEXT: #NO_APP
; CHECK-NEXT: jmp .LBB3_3
entry:
callbr void asm sideeffect "ja $0", "X,~{dirflag},~{fpsr},~{flags}"(i8* blockaddress(@test4, %quux))
to label %asm.fallthrough [label %quux]
asm.fallthrough: ; preds = %entry
callbr void asm sideeffect "ja ${0:l}", "X,~{dirflag},~{fpsr},~{flags}"(i8* blockaddress(@test4, %quux))
to label %cleanup [label %quux]
quux: ; preds = %asm.fallthrough, %entry
br label %cleanup
cleanup: ; preds = %asm.fallthrough, %quux
ret void
}