011e4abb49
```
MCRegister getX86SubSuperRegister*(MCRegister Reg, unsigned Size,
bool High = false);
```
A strange behavior of the functions `getX86SubSuperRegister*` was
introduced by llvm-svn:145579: The returned register may not
match the parameters when a 8-bit high register is required.
And llvm-svn: 175762 refined the code and dropped the comments, then we
knew nothing happened there from the code :-(
These two functions are only called with `Size=8` and `High=true` in two places.
One is in `X86FixupBWInsts.cpp` for liveness of registers and the other is in
`X86AsmPrinter.cpp` for inline asm.
For the first one, we provide an alternative in this patch.
For the second one, the strange behaviour caused a bug that an erorr was not reported for mismatched modifier.
```
void f() {
char x;
asm volatile ("mov %%ah, %h0" :"=r"(x)::"%eax", "%ebx", "%ecx", "%edx", "edi", "esi");
}
```
```
$ gcc -S test.c
error: extended registers have no high halves
```
```
$ clang -S test.c
no error
```
so we fix the bug in this patch.
`getX86SubSuperRegister` is just a wrapper of `getX86SubSuperRegisterOrZero` with a `assert`.
I belive we should remove the latter.
Reviewed By: pengfei
Differential Revision: https://reviews.llvm.org/D142834
10 lines
299 B
LLVM
10 lines
299 B
LLVM
; RUN: not llc < %s -mtriple=x86_64-unknown-unknown 2>&1 | FileCheck %s
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; CHECK: error: invalid operand in inline asm: 'mov %ah, ${0:h}'
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define void @test1() {
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entry:
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%0 = tail call i8 asm sideeffect "mov %ah, ${0:h}", "=r,~{eax},~{ebx},~{ecx},~{edx},~{dirflag},~{fpsr},~{flags}"()
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ret void
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}
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