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bolt/test/X86/jmp-after-ret.s
18	This is default syntax for asm and called numeric label: https://docs.oracle.com/cd/E19120-01/open.solaris/817-5477/esqaq/index.html . I've checked the objdump for this (x86) and it works fine, and I'm sure about arm too :) I often see such syntax in linux kernel, so I think it is OK if you don't mind :)

bolt/test/X86/jmp-after-ret.s
18	Thanks for clarification. I wasn’t familiar with this syntax and it looks confusing, but as long as it works let’s keep it.

LGTM

This revision is now accepted and ready to land.Jan 19 2022, 10:50 AM

This revision was automatically updated to reflect the committed changes.

yota9 marked 2 inline comments as done.

Revision Contents

Path

Size

bolt/

lib/

Core/

3 lines

test/

AArch64/

24 lines

X86/

24 lines

Show First 20 Lines • Show All 2,027 Lines • ▼ Show 20 Lines	if (!InsertBB) {
// It must be a fallthrough or unreachable code. Create a new block unless		// It must be a fallthrough or unreachable code. Create a new block unless
// we see an unconditional branch following a conditional one. The latter		// we see an unconditional branch following a conditional one. The latter
// should not be a conditional tail call.		// should not be a conditional tail call.
assert(PrevBB && "no previous basic block for a fall through");		assert(PrevBB && "no previous basic block for a fall through");
MCInst *PrevInstr = PrevBB->getLastNonPseudoInstr();		MCInst *PrevInstr = PrevBB->getLastNonPseudoInstr();
assert(PrevInstr && "no previous instruction for a fall through");		assert(PrevInstr && "no previous instruction for a fall through");
if (MIB->isUnconditionalBranch(Instr) &&		if (MIB->isUnconditionalBranch(Instr) &&
!MIB->isUnconditionalBranch(*PrevInstr) &&		!MIB->isUnconditionalBranch(*PrevInstr) &&
!MIB->getConditionalTailCall(*PrevInstr)) {		!MIB->getConditionalTailCall(*PrevInstr) &&
		!MIB->isReturn(*PrevInstr)) {
// Temporarily restore inserter basic block.		// Temporarily restore inserter basic block.
InsertBB = PrevBB;		InsertBB = PrevBB;
} else {		} else {
MCSymbol *Label;		MCSymbol *Label;
{		{
auto L = BC.scopeLock();		auto L = BC.scopeLock();
Label = BC.Ctx->createNamedTempSymbol("FT");		Label = BC.Ctx->createNamedTempSymbol("FT");
}		}
▲ Show 20 Lines • Show All 2,452 Lines • Show Last 20 Lines

				## This test checks that the unreachable unconditional branch is removed
				## if it is located after return instruction.

				# REQUIRES: system-linux

				# RUN: llvm-mc -filetype=obj -triple aarch64-unknown-unknown \
				# RUN: %s -o %t.o
				# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q
				# RUN: llvm-bolt %t.exe -o %t.bolt \| FileCheck %s

				# CHECK: UCE removed 1 blocks

				.text
				.align 4
				.global main
				.type main, %function
				main:
				b.eq 1f
				ret
				b main
				1:
				mov x1, #1
				ret
				.size main, .-main

				## This test checks that the unreachable unconditional branch is removed
				## if it is located after return instruction.

				# REQUIRES: system-linux

				# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown \
				# RUN: %s -o %t.o
				# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q
				# RUN: llvm-bolt %t.exe -o %t.bolt \| FileCheck %s

				# CHECK: UCE removed 1 blocks

				.text
				.globl main
				.type main, %function
				.size main, .Lend-main
				main:
				je 1f
				AmirUnsubmitted Done Reply Inline Actions Are you sure `1f` here means the label and not a hex offset? Can you please use `.L1` instead to make it explicit? Amir: Are you sure `1f` here means the label and not a hex offset? Can you please use `.L1` instead…
				yota9AuthorUnsubmitted Done Reply Inline Actions This is default syntax for asm and called numeric label: https://docs.oracle.com/cd/E19120-01/open.solaris/817-5477/esqaq/index.html . I've checked the objdump for this (x86) and it works fine, and I'm sure about arm too :) I often see such syntax in linux kernel, so I think it is OK if you don't mind :) yota9: This is default syntax for asm and called numeric label: https://docs.oracle.com/cd/E19120…
				AmirUnsubmitted Done Reply Inline Actions Thanks for clarification. I wasn’t familiar with this syntax and it looks confusing, but as long as it works let’s keep it. Amir: Thanks for clarification. I wasn’t familiar with this syntax and it looks confusing, but as…
				retq
				jmp main
				1:
				movl $0x2, %ebx
				retq
				.Lend: