[PATCH] [PR42093] [arm] [thumb2] disable tree-dce for test

[PATCH] [PR42093] [arm] [thumb2] disable tree-dce for test

[Alexandre Oliva]

CD-DCE introduces blocks to share common PHI nodes, which replaces a
backwards branch that used to prevent the thumb2 jump table shortening
that PR42093 tested for.  In order to keep on testing that the
backward branch prevents the jumptable shortening, disable tree-dce.

Regstraped on x86_64-linux-gnu, also tested with crosses to riscv64-elf
and arm-eabi.  Ok to install?


for  gcc/testsuite/ChangeLog

	PR target/42093
	* gcc.target/arm/pr42093.c: Disable tree-dce.
---
 gcc/testsuite/gcc.target/arm/pr42093.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.target/arm/pr42093.c b/gcc/testsuite/gcc.target/arm/pr42093.c
index 7ba2f933eef81..69b1470607c7f 100644
--- a/gcc/testsuite/gcc.target/arm/pr42093.c
+++ b/gcc/testsuite/gcc.target/arm/pr42093.c
@@ -1,4 +1,4 @@
-/* { dg-options "-mthumb -O2 -fno-reorder-blocks" }  */
+/* { dg-options "-mthumb -O2 -fno-reorder-blocks -fno-tree-dce" }  */
 /* { dg-require-effective-target arm_thumb2_ok } */
 /* { dg-final { scan-assembler-not "tbb" } } */
 /* { dg-final { scan-assembler-not "tbh" } } */

-- 
Alexandre Oliva, happy hacker                https://FSFLA.org/blogs/lxo/
   Free Software Activist                       GNU Toolchain Engineer
Disinformation flourishes because many people care deeply about injustice
but very few check the facts.  Ask me about <https://stallmansupport.org>

Re: [PATCH] [PR42093] [arm] [thumb2] disable tree-dce for test

[Richard Earnshaw]

On 02/12/2022 09:26, Alexandre Oliva via Gcc-patches wrote:
> 
> CD-DCE introduces blocks to share common PHI nodes, which replaces a
> backwards branch that used to prevent the thumb2 jump table shortening
> that PR42093 tested for.  In order to keep on testing that the
> backward branch prevents the jumptable shortening, disable tree-dce.
> 
> Regstraped on x86_64-linux-gnu, also tested with crosses to riscv64-elf
> and arm-eabi.  Ok to install?
> 
>  > for  gcc/testsuite/ChangeLog
> 
> 	PR target/42093
> 	* gcc.target/arm/pr42093.c: Disable tree-dce.

OK.

R.

> ---
>   gcc/testsuite/gcc.target/arm/pr42093.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/gcc/testsuite/gcc.target/arm/pr42093.c b/gcc/testsuite/gcc.target/arm/pr42093.c
> index 7ba2f933eef81..69b1470607c7f 100644
> --- a/gcc/testsuite/gcc.target/arm/pr42093.c
> +++ b/gcc/testsuite/gcc.target/arm/pr42093.c
> @@ -1,4 +1,4 @@
> -/* { dg-options "-mthumb -O2 -fno-reorder-blocks" }  */
> +/* { dg-options "-mthumb -O2 -fno-reorder-blocks -fno-tree-dce" }  */
>   /* { dg-require-effective-target arm_thumb2_ok } */
>   /* { dg-final { scan-assembler-not "tbb" } } */
>   /* { dg-final { scan-assembler-not "tbh" } } */
>