https://bugs.llvm.org/show_bug.cgi?id=42830
Bug ID: 42830
Summary: Incorrect register allocation for inline assembly with
4 outputs
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: gli...@google.com
CC: craig.top...@gmail.com, llvm-bugs@lists.llvm.org,
llvm-...@redking.me.uk, spatel+l...@rotateright.com
When compiling the following code:
$ cat bar.c
char foo();
int bar() {
char x1 = foo();
char x2 = foo();
char x3 = foo();
char y1, y2, y3, y4;
asm("mov $1, %k0\nmov $2, %k1\nmov $3, %k2\nmov $4, %k3" : "=r"(y1),
"=r"(y2), "=r"(y3), "=r"(y4));
return x1 + x2 + y1 + y2 + y3 + y4;
}
with -m32, Clang uses EAX twice to return 1 and 4 from the inline assembly:
$ clang bar.c -c -m32
$ objdump -dr bar.o
00000000 <bar>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 57 push %edi
4: 56 push %esi
5: 83 ec 10 sub $0x10,%esp
8: e8 fc ff ff ff call 9 <bar+0x9>
9: R_386_PC32 foo
d: 88 45 f7 mov %al,-0x9(%ebp)
10: e8 fc ff ff ff call 11 <bar+0x11>
11: R_386_PC32 foo
15: 88 45 f6 mov %al,-0xa(%ebp)
18: e8 fc ff ff ff call 19 <bar+0x19>
19: R_386_PC32 foo
1d: 88 45 f5 mov %al,-0xb(%ebp)
20: b8 01 00 00 00 mov $0x1,%eax
25: b9 02 00 00 00 mov $0x2,%ecx
2a: ba 03 00 00 00 mov $0x3,%edx
2f: b8 04 00 00 00 mov $0x4,%eax
Without -m32 Clang returns 1 and 4 in EAX and ESI, respectively.
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
