Hello!
Attached patch optimizes x86_64 gtm_jmpbuf layout to avoid copying
return address. Optimized layout uses the same trick as x86_32 - call
used registers are saved just below return address. And there is just
enough space in the call alignment hole to put all of them there.
2012-01-24 Uros Bizjak <ubiz...@gmail.com>
* config/x86/target.h (gtm_jmpbuf) [__x86_64__]: Move rip to the
end of struct.
* config/x86/sjlj.S (_ITM_beginTransaction) [__x86_64__]: Update
offset values. Do not copy return address. Decrement stack
by 56 bytes only.
(GTM_longjump) [__x86_64__]: Update offset values.
Tested on x86_64-pc-linux-gnu.
OK for mainline?
BTW: Do we really need move at the end of GTM_longjump:
movq 48(%rsi), %r15
movq 56(%rsi), %rdx
>> movl %edi, %eax
cfi_def_cfa(%rcx, 0)
cfi_register(%rip, %rdx)
movq %rcx, %rsp
jmp *%rdx
Uros.
Index: config/x86/sjlj.S
===================================================================
--- config/x86/sjlj.S (revision 183449)
+++ config/x86/sjlj.S (working copy)
@@ -61,20 +61,18 @@ SYM(_ITM_beginTransaction):
cfi_startproc
#ifdef __x86_64__
leaq 8(%rsp), %rax
- movq (%rsp), %r8
- subq $72, %rsp
- cfi_def_cfa_offset(80)
+ subq $56, %rsp
+ cfi_def_cfa_offset(64)
movq %rax, (%rsp)
- movq %r8, 8(%rsp)
- movq %rbx, 16(%rsp)
- movq %rbp, 24(%rsp)
- movq %r12, 32(%rsp)
- movq %r13, 40(%rsp)
- movq %r14, 48(%rsp)
- movq %r15, 56(%rsp)
+ movq %rbx, 8(%rsp)
+ movq %rbp, 16(%rsp)
+ movq %r12, 24(%rsp)
+ movq %r13, 32(%rsp)
+ movq %r14, 40(%rsp)
+ movq %r15, 48(%rsp)
movq %rsp, %rsi
call SYM(GTM_begin_transaction)
- addq $72, %rsp
+ addq $56, %rsp
cfi_def_cfa_offset(8)
ret
#else
@@ -115,13 +113,13 @@ SYM(GTM_longjmp):
cfi_startproc
#ifdef __x86_64__
movq (%rsi), %rcx
- movq 8(%rsi), %rdx
- movq 16(%rsi), %rbx
- movq 24(%rsi), %rbp
- movq 32(%rsi), %r12
- movq 40(%rsi), %r13
- movq 48(%rsi), %r14
- movq 56(%rsi), %r15
+ movq 8(%rsi), %rbx
+ movq 16(%rsi), %rbp
+ movq 24(%rsi), %r12
+ movq 32(%rsi), %r13
+ movq 40(%rsi), %r14
+ movq 48(%rsi), %r15
+ movq 56(%rsi), %rdx
movl %edi, %eax
cfi_def_cfa(%rcx, 0)
cfi_register(%rip, %rdx)
Index: config/x86/target.h
===================================================================
--- config/x86/target.h (revision 183449)
+++ config/x86/target.h (working copy)
@@ -29,13 +29,13 @@ namespace GTM HIDDEN {
typedef struct gtm_jmpbuf
{
void *cfa;
- unsigned long rip;
unsigned long rbx;
unsigned long rbp;
unsigned long r12;
unsigned long r13;
unsigned long r14;
unsigned long r15;
+ unsigned long rip;
} gtm_jmpbuf;
#else
typedef struct gtm_jmpbuf
