Re: [PATCH] testsuite: arm: Update expected asm in no-literal-pool-m0.c

[Christophe Lyon]

On 10/14/24 16:40, Torbjorn SVENSSON wrote:
Hi Christophe,

On 2024-10-14 14:16, Christophe Lyon wrote:
Hi Torbjörn,


On 10/13/24 19:37, Torbjörn SVENSSON wrote:
Ok for trunk?

--

With the changes in r15-1579-g792f97b44ff, the constants have been
updated. This patch aligns the constants in the test cases with the
updated implementation.


Could you share a bit more details? In particular, IIUC, since the 
constants used now are different, why do you introduce new 
alternatives, rather than replace the old expected constants?

Do we now generate both old & new versions, depending on some flags?

The constants depends on if some optimization step is included or not. I 
don't understand how this works, but the changeset that Richard merged 
in the above commit id does cause this need.
I think the constants switch with -O2, but I don't know exactly what 
part that enables it.

 From my point of view, the mov instruction could always us the higher 
value and then do a lower amount of shifts, but don't know if that's 
easy to achieve or not.

Indeed, these tests are exercised with several optimization levels from 
-O0 to -O3 and -Os, and late-combine is only enabled at -O2 and above, 
including -Os. So I guess the previous value is still used at -O0 and -O1.

Thanks for the clarification.

LGTM.

Christophe

Kind regards,
Torbjörn


FTR, this is also tracked by https://linaro.atlassian.net/browse/GNU-1269


Thanks,

Christophe

gcc/testsuite/ChangeLog:

    * gcc.target/arm/pure-code/no-literal-pool-m0.c: Update expected
    asm.

Signed-off-by: Torbjörn SVENSSON <torbjorn.svens...@foss.st.com>
---
  .../arm/pure-code/no-literal-pool-m0.c        | 29 ++++++++++++++-----
  1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/gcc/testsuite/gcc.target/arm/pure-code/no-literal-pool- 
m0.c b/gcc/testsuite/gcc.target/arm/pure-code/no-literal-pool-m0.c
index bd6f4af183b..effaf8b60b6 100644
--- a/gcc/testsuite/gcc.target/arm/pure-code/no-literal-pool-m0.c
+++ b/gcc/testsuite/gcc.target/arm/pure-code/no-literal-pool-m0.c
@@ -95,8 +95,13 @@ test_65536 ()
  /*
  ** test_0x123456:
  **    ...
+** (
  **    movs    r[0-3], #18
  **    lsls    r[0-3], r[0-3], #8
+** |
+**    movs    r[0-3], #144
+**    lsls    r[0-3], r[0-3], #5
+** )
  **    adds    r[0-3], r[0-3], #52
  **    lsls    r[0-3], r[0-3], #8
  **    adds    r[0-3], r[0-3], #86
@@ -125,18 +130,16 @@ test_0x1123456 ()
    return 0x1123456;
  }
-/* With -Os, we generate:
-   movs r0, #16
-   lsls r0, r0, r0
-   With the other optimization levels, we generate:
-   movs r0, #16
-   lsls r0, r0, #16
-   hence the two alternatives.  */
  /*
  ** test_0x1000010:
  **    ...
+** (
  **    movs    r[0-3], #16
-**    lsls    r[0-3], r[0-3], (#16|r[0-3])
+**    lsls    r[0-3], r[0-3], #16
+** |
+**    movs    r[0-3], #128
+**    lsls    r[0-3], r[0-3], #13
+** )
  **    adds    r[0-3], r[0-3], #1
  **    lsls    r[0-3], r[0-3], #4
  **    ...
@@ -150,8 +153,13 @@ test_0x1000010 ()
  /*
  ** test_0x1000011:
  **    ...
+** (
  **    movs    r[0-3], #1
  **    lsls    r[0-3], r[0-3], #24
+** |
+**    movs    r[0-3], #128
+**    lsls    r[0-3], r[0-3], #17
+** )
  **    adds    r[0-3], r[0-3], #17
  **    ...
  */
@@ -164,8 +172,13 @@ test_0x1000011 ()
  /*
  ** test_m8192:
  **    ...
+** (
  **    movs    r[0-3], #1
  **    lsls    r[0-3], r[0-3], #13
+** |
+**    movs    r[0-3], #128
+**    lsls    r[0-3], r[0-3], #6
+** )
  **    rsbs    r[0-3], r[0-3], #0
  **    ...
  */