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| author | Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> | 2016-05-13 09:23:28 +0000 |
|---|---|---|
| committer | Ramana Radhakrishnan <ramana@gcc.gnu.org> | 2016-05-13 09:23:28 +0000 |
| commit | 43203dea1afa87140a0f045f2c2182943247065f (patch) | |
| tree | ec00ce3d8d49a2c80e8e91fcf56ef29defe59ba8 | |
| parent | 44cb09ea6b2164e8392e3001b0ba5b93093bfa07 (diff) | |
| download | gcc-43203dea1afa87140a0f045f2c2182943247065f.zip gcc-43203dea1afa87140a0f045f2c2182943247065f.tar.gz gcc-43203dea1afa87140a0f045f2c2182943247065f.tar.bz2 | |
Set TARGET_OMIT_STRUCT_RETURN_REG to true
The reason this caught my eye on aarch64 is because
the return value register (x0) is not identical to the register in which
the hidden parameter for AArch64 is set (x8). Thus setting this to true
seems to be quite reasonable and shaves off 100 odd mov x0, x8's from
cc1 in a bootstrap build.
I don't expect this to make a huge impact on performance but as they
say every little counts. The AAPCS64 is quite explicit about not
requiring that the contents of x8 be kept live.
Bootstrapped and regression tested on aarch64.
Ok to apply ?
Ramana
gcc/
* config/aarch64/aarch64.c (TARGET_OMIT_STRUCT_RETURN_REG): Set to
true.
gcc/testsuite
* gcc.target/aarch64/struct_return.c: New test.
From-SVN: r236197
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/config/aarch64/aarch64.c | 3 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/aarch64/struct_return.c | 31 |
4 files changed, 43 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 93fa743..87f5eaf 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2016-05-13 Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> + + * config/aarch64/aarch64.c (TARGET_OMIT_STRUCT_RETURN_REG): Set + to true. + 2016-05-13 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> PR target/71080 diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index 9995494..7e0e3b9 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -14232,6 +14232,9 @@ aarch64_optab_supported_p (int op, machine_mode, machine_mode, #undef TARGET_OPTAB_SUPPORTED_P #define TARGET_OPTAB_SUPPORTED_P aarch64_optab_supported_p +#undef TARGET_OMIT_STRUCT_RETURN_REG +#define TARGET_OMIT_STRUCT_RETURN_REG true + struct gcc_target targetm = TARGET_INITIALIZER; #include "gt-aarch64.h" diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index fd0702b..333bec6 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2016-05-13 Ramana Radhakrishnan <ramana.radhakrishnan@arm.com> + + * gcc.target/aarch64/struct_return.c: New test. + 2016-05-12 Marek Polacek <polacek@redhat.com> PR c/70756 diff --git a/gcc/testsuite/gcc.target/aarch64/struct_return.c b/gcc/testsuite/gcc.target/aarch64/struct_return.c new file mode 100644 index 0000000..6d90b7e --- /dev/null +++ b/gcc/testsuite/gcc.target/aarch64/struct_return.c @@ -0,0 +1,31 @@ +/* Test the absence of a spurious move from x8 to x0 for functions + return structures. */ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +struct s +{ + long x; + long y; + long z; +}; + +struct s __attribute__((noinline)) +foo (long a, long d, long c) +{ + struct s b; + b.x = a; + b.y = d; + b.z = c; + return b; +} + +int +main (void) +{ + struct s x; + x = foo ( 10, 20, 30); + return x.x + x.y + x.z; +} + +/* { dg-final { scan-assembler-not "mov\tx0, x8" } } */ |