On 2024-11-08 15:30, Richard Earnshaw (lists) wrote:
On 14/10/2024 16:28, Christophe Lyon wrote:On 10/14/24 16:40, Torbjorn SVENSSON wrote: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.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.Thanks for the clarification. LGTM. ChristopheKind regards, TorbjörnFTR, this is also tracked by https://linaro.atlassian.net/browse/ GNU-1269Thanks, Christophegcc/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.cindex 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 ** ... */Do we really need to care about the precise assembler output at all the different optimization levels? Isn't it enough to simply check that we don't get a literal pool entry? Eg to scan forldr r[0-7], .Lnnnn *not* being in the generated code.
Do you want me to remove all the function-bodies and just add
/* { dg-final { scan-assembler-not "\tldr\tr[0-9]+, \\.L[0-9]+" } } */
or, do you want me to only change the functions that I am touching in my
patch? (I've not tested the statement above, I will do that prior to
sending it...).
Kind regards, Torbjörn
R.
