[PATCH][AArch64] PR target/66731 Fix fnmul insn with -frounding-math

[James Greenhalgh]

On Mon, Jul 06, 2015 at 09:20:39AM +0100, Szabolcs Nagy wrote:
> fnmul was modeled as (-a)*b instead of -(a*b), which is wrong with
> -frounding-math, so the correct pattern is added too and the other
> one is only used if !flag_rounding_math.
> 
> This affects a glibc math test, similar fix will be needed for ARM.
> 
> Tested with aarch64-none-linux-gnu cross compiler.
> is this OK?
> 
> gcc/Changelog:
> 
> 2015-07-06  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	PR target/66731
> 	* config/aarch64/aarch64.md (fnmul<mode>3): Handle -frounding-math.
> 
> gcc/testsuite/Changelog:
> 
> 2015-07-06  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* gcc.target/aarch64/fnmul-1.c: New.
> 	* gcc.target/aarch64/fnmul-2.c: New.
> 	* gcc.target/aarch64/fnmul-3.c: New.
> 	* gcc.target/aarch64/fnmul-4.c: New.

OK.

Please make sure in a follow-up patch that the costing logic in
aarch64_rtx_costs also gets updated.

Thanks,
James


> diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
> index 2d56a75..1e343fa 100644
> --- a/gcc/config/aarch64/aarch64.md
> +++ b/gcc/config/aarch64/aarch64.md
> @@ -4175,6 +4175,16 @@
>          (mult:GPF
>  		 (neg:GPF (match_operand:GPF 1 "register_operand" "w"))
>  		 (match_operand:GPF 2 "register_operand" "w")))]
> +  "TARGET_FLOAT && !flag_rounding_math"
> +  "fnmul\\t%<s>0, %<s>1, %<s>2"
> +  [(set_attr "type" "fmul<s>")]
> +)
> +
> +(define_insn "*fnmul<mode>3"
> +  [(set (match_operand:GPF 0 "register_operand" "=w")
> +        (neg:GPF (mult:GPF
> +		 (match_operand:GPF 1 "register_operand" "w")
> +		 (match_operand:GPF 2 "register_operand" "w"))))]
>    "TARGET_FLOAT"
>    "fnmul\\t%<s>0, %<s>1, %<s>2"
>    [(set_attr "type" "fmul<s>")]
> diff --git a/gcc/testsuite/gcc.target/aarch64/fnmul-1.c b/gcc/testsuite/gcc.target/aarch64/fnmul-1.c
> new file mode 100644
> index 0000000..7ec38e0
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/fnmul-1.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +double
> +foo_d (double a, double b)
> +{
> +	/* { dg-final { scan-assembler "fnmul\\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" } } */
> +	return -a * b;
> +}
> +
> +float
> +foo_s (float a, float b)
> +{
> +	/* { dg-final { scan-assembler "fnmul\\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" } } */
> +	return -a * b;
> +}
> diff --git a/gcc/testsuite/gcc.target/aarch64/fnmul-2.c b/gcc/testsuite/gcc.target/aarch64/fnmul-2.c
> new file mode 100644
> index 0000000..f05ee79
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/fnmul-2.c
> @@ -0,0 +1,18 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -frounding-math" } */
> +
> +double
> +foo_d (double a, double b)
> +{
> +	/* { dg-final { scan-assembler "fneg\\td\[0-9\]+, d\[0-9\]+" } } */
> +	/* { dg-final { scan-assembler "fmul\\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" } } */
> +	return -a * b;
> +}
> +
> +float
> +foo_s (float a, float b)
> +{
> +	/* { dg-final { scan-assembler "fneg\\ts\[0-9\]+, s\[0-9\]+" } } */
> +	/* { dg-final { scan-assembler "fmul\\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" } } */
> +	return -a * b;
> +}
> diff --git a/gcc/testsuite/gcc.target/aarch64/fnmul-3.c b/gcc/testsuite/gcc.target/aarch64/fnmul-3.c
> new file mode 100644
> index 0000000..301e9cd
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/fnmul-3.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2" } */
> +
> +double
> +foo_d (double a, double b)
> +{
> +	/* { dg-final { scan-assembler "fnmul\\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" } } */
> +	return -(a * b);
> +}
> +
> +float
> +foo_s (float a, float b)
> +{
> +	/* { dg-final { scan-assembler "fnmul\\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" } } */
> +	return -(a * b);
> +}
> diff --git a/gcc/testsuite/gcc.target/aarch64/fnmul-4.c b/gcc/testsuite/gcc.target/aarch64/fnmul-4.c
> new file mode 100644
> index 0000000..9b9bf1b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/fnmul-4.c
> @@ -0,0 +1,16 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -frounding-math" } */
> +
> +double
> +foo_d (double a, double b)
> +{
> +	/* { dg-final { scan-assembler "fnmul\\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" } } */
> +	return -(a * b);
> +}
> +
> +float
> +foo_s (float a, float b)
> +{
> +	/* { dg-final { scan-assembler "fnmul\\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" } } */
> +	return -(a * b);
> +}