https://llvm.org/bugs/show_bug.cgi?id=25945
Bug ID: 25945
Summary: [x64] Improper CFI used for function clobbering FLAGS
register
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: david.majne...@gmail.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
consider:
define i64 @test_intervening_call(i64* %foo, i64 %bar, i64 %baz) {
%cx = cmpxchg i64* %foo, i64 %bar, i64 %baz seq_cst seq_cst
%v = extractvalue { i64, i1 } %cx, 0
%p = extractvalue { i64, i1 } %cx, 1
call void asm sideeffect "", "~{cc},~{dirflag},~{fpsr},~{flags}"()
br i1 %p, label %t, label %f
t:
ret i64 42
f:
ret i64 0
}
this results in:
test_intervening_call: # @test_intervening_call
.Ltmp0:
.seh_proc test_intervening_call
# BB#0:
.Ltmp1:
.seh_endprologue
movq %rdx, %rax
lock cmpxchgq %r8, (%rcx)
pushfq <---- uh, oh...
popq %rax
#APP
#NO_APP
pushq %rax
popfq
jne .LBB0_2
# BB#1: # %t
movl $42, %eax
retq
.LBB0_2: # %f
xorl %eax, %eax
retq
.seh_handlerdata
Notice how we are manipulating the stack pointer even though we don't have a
frame pointer.
--
You are receiving this mail because:
You are on the CC list for the bug.
_______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
