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| author | Stefan Liebler <stli@linux.ibm.com> | 2020-06-26 09:45:11 +0200 |
|---|---|---|
| committer | Stefan Liebler <stli@linux.ibm.com> | 2020-06-26 09:45:11 +0200 |
| commit | 1d21fb1061cbeb50414a8f371abb36548d90f150 (patch) | |
| tree | f1bc239f508120eb85c1d8c53b51906edbe72500 | |
| parent | 0792c8ae1aebf538de45ff9a0e2e401a60525de2 (diff) | |
| download | glibc-1d21fb1061cbeb50414a8f371abb36548d90f150.tar.gz glibc-1d21fb1061cbeb50414a8f371abb36548d90f150.tar.xz glibc-1d21fb1061cbeb50414a8f371abb36548d90f150.zip | |
S390: Optimize __memset_z196.
It turned out that an 256b-mvc instruction which depends on the result of a previous 256b-mvc instruction is counterproductive. Therefore this patch adjusts the 256b-loop by storing the first byte with stc and setting the remaining 255b with mvc. Now the 255b-mvc instruction depends on the stc instruction.
| -rw-r--r-- | sysdeps/s390/memset-z900.S | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/sysdeps/s390/memset-z900.S b/sysdeps/s390/memset-z900.S index ca3eac0522..1e0c334156 100644 --- a/sysdeps/s390/memset-z900.S +++ b/sysdeps/s390/memset-z900.S @@ -157,28 +157,27 @@ ENTRY(MEMSET_Z196) # if !defined __s390x__ llgfr %r4,%r4 # endif /* !defined __s390x__ */ - ltgr %r4,%r4 - je .L_Z196_4 + clgfi %r4,1 + jl .L_Z196_4 # n == 0 stc %r3,0(%r2) + je .L_Z196_4 # n == 1 + aghi %r4,-2 lgr %r1,%r2 - cghi %r4,1 - je .L_Z196_4 - aghi %r4,-2 - srlg %r5,%r4,8 - ltgr %r5,%r5 - jne .L_Z196_1 + risbg %r5,%r4,8,128+63,56 # r5 = n / 256 + jne .L_Z196_1 # Jump away if r5 != 0 .L_Z196_3: exrl %r4,.L_Z196_17 .L_Z196_4: br %r14 .L_Z196_1: cgfi %r5,1048576 - jh __memset_mvcle # Switch to mvcle for >256MB + jh __memset_mvcle # Switch to mvcle for >256MB .L_Z196_2: pfd 2,1024(%r1) - mvc 1(256,%r1),0(%r1) + mvc 1(255,%r1),0(%r1) aghi %r5,-1 la %r1,256(%r1) + stc %r3,0(%r1) jne .L_Z196_2 j .L_Z196_3 .L_Z196_17: |