On 01-07-14 19:26, Jeff Law wrote:
On 07/01/14 09:51, Yufeng Zhang wrote:
Hi,
This patch resolves a conflict between the aapcs64 test framework for
func-ret tests and the optimization option -fuse-caller-save, which was
enabled by default at -O1 or above recently.
Minor detail: it's enabled by default at -O2 or above:
...
{ OPT_LEVELS_2_PLUS, OPT_fuse_caller_save, NULL, 1 },
...
Basically, the test framework has an inline-assembly based mechanism in
place which invokes the test facility function right on the return of a
tested function.
>> The compiler with -fuse-caller-save is unable to
>> identify the unconventional call graph and carries out the optimization
>> regardless.
AFAIU, we're overwriting the return register to implement a function call at
return in order to see the exact state of registers at return:
...
__attribute__ ((noinline)) unsigned char
func_return_val_0 (int i, double d, unsigned char t)
{
asm (""::"r" (i),"r" (d));
asm volatile ("mov %0, x30" : "=r" (saved_return_address));
asm volatile ("mov x30, %0" : : "r" ((unsigned long long) myfunc));
return t;
}
...
But we're not informing the compiler that a hidden function call takes place.
This patch fixes that, and there's no need to disable fuse-caller-save.
Tested with aarch64 build. OK for trunk?
Thanks,
- Tom
2014-07-08 Tom de Vries <t...@codesourcery.com>
* gcc.target/aarch64/aapcs64/aapcs64.exp
(additional_flags_for_func_ret): Remove.
(func-ret-*.c): Use additional_flags.
* gcc.target/aarch64/aapcs64/abitest-2.h (FUNC_VAL_CHECK): Add missing
call_used_regs clobbers.
Index: gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp
===================================================================
--- gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp (revision 212294)
+++ gcc/testsuite/gcc.target/aarch64/aapcs64/aapcs64.exp (working copy)
@@ -48,15 +48,11 @@ foreach src [lsort [glob -nocomplain $sr
}
# Test function return value.
-# Disable -fuse-caller-save to prevent the compiler from generating
-# conflicting code.
-set additional_flags_for_func_ret $additional_flags
-append additional_flags_for_func_ret " -fno-use-caller-save"
foreach src [lsort [glob -nocomplain $srcdir/$subdir/func-ret-*.c]] {
if {[runtest_file_p $runtests $src]} {
c-torture-execute [list $src \
$srcdir/$subdir/abitest.S] \
- $additional_flags_for_func_ret
+ $additional_flags
}
}
Index: gcc/testsuite/gcc.target/aarch64/aapcs64/abitest-2.h
===================================================================
--- gcc/testsuite/gcc.target/aarch64/aapcs64/abitest-2.h (revision 212294)
+++ gcc/testsuite/gcc.target/aarch64/aapcs64/abitest-2.h (working copy)
@@ -80,10 +80,18 @@ __attribute__ ((noinline)) type FUNC_NAM
The previous approach of sequentially calling myfunc right after \
this function does not guarantee myfunc see the exact register \
content, as compiler may emit code in between the two calls, \
- especially during the -O0 codegen. */ \
+ especially during the -O0 codegen. \
+ However, since we're doing a call, we need to clobber all call \
+ used regs. */ \
asm volatile ("mov %0, x30" : "=r" (saved_return_address)); \
- asm volatile ("mov x30, %0" : : "r" ((unsigned long long) myfunc)); \
- return t; \
+ asm volatile ("mov x30, %0" : : "r" ((unsigned long long) myfunc) : \
+ "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7", \
+ "x8", "x9", "x10", "x11", "x12", "x13", "x14", "x15", \
+ "x16", "x17", "x18", \
+ "v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7", \
+ "v16", "v17", "v18", "v19", "v20", "v21", "v22", "v23", \
+ "v24", "v25", "v26", "v27", "v28", "v29", "v30", "v31");\
+ return t; \
}
#include TESTFILE
