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add generation of unnecessary push/pop around calls

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35241 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2007-03-21 21:16:39 +00:00
parent cfe0798a9e
commit aceaf5d26e
1 changed files with 42 additions and 0 deletions
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42
lib/Target/X86/README.txt
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@ -989,3 +989,45 @@ _foo:
ret
//===---------------------------------------------------------------------===//
We use push/pop of stack space around calls in situations where we don't have to.
Call to f below produces:
subl $16, %esp <<<<<
movl %eax, (%esp)
call L_f$stub
addl $16, %esp <<<<<
The stack push/pop can be moved into the prolog/epilog. It does this because it's
building the frame pointer, but this should not be sufficient, only the use of alloca
should cause it to do this.
(There are other issues shown by this code, but this is one.)
typedef struct _range_t {
float fbias;
float fscale;
int ibias;
int iscale;
int ishift;
unsigned char lut[];
} range_t;
struct _decode_t {
int type:4;
int unit:4;
int alpha:8;
int N:8;
int bpc:8;
int bpp:16;
int skip:8;
int swap:8;
const range_t*const*range;
};
typedef struct _decode_t decode_t;
extern int f(const decode_t* decode);
int decode_byte (const decode_t* decode) {
if (decode->swap != 0)
return f(decode);
return 0;
}