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112 lines
3.4 KiB
112 lines
3.4 KiB
From 561857f53a543684862c2b6d2308bc13affa2a18 Mon Sep 17 00:00:00 2001 |
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From: Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com> |
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Date: Tue, 18 Aug 2015 22:40:56 +0530 |
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Subject: [PATCH] powerpc: Handle worstcase behavior in strstr() for POWER7 |
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Instead of checking needle length, constant 'n' number of comparisons |
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is checked to fall back to default implementation. This patch is tested |
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on powerpc64 and powerpc64le. |
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2015-08-25 Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com> |
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* sysdeps/powerpc/powerpc64/power7/strstr.S: Handle worst case. |
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(cherry picked from commit fe7faec3e56a8dd64f78023a2f4a74fc8d42e79f) |
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--- |
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ChangeLog | 4 ++++ |
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sysdeps/powerpc/powerpc64/power7/strstr.S | 22 +++++++++++++++------- |
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2 files changed, 19 insertions(+), 7 deletions(-) |
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diff --git a/ChangeLog b/ChangeLog |
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index cf95a84..5cbd6d6 100644 |
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diff --git a/sysdeps/powerpc/powerpc64/power7/strstr.S b/sysdeps/powerpc/powerpc64/power7/strstr.S |
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index bfb0c49..fb3c810 100644 |
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--- a/sysdeps/powerpc/powerpc64/power7/strstr.S |
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+++ b/sysdeps/powerpc/powerpc64/power7/strstr.S |
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@@ -23,6 +23,8 @@ |
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/* The performance gain is obtained using aligned memory access, load |
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* doubleword and usage of cmpb instruction for quicker comparison. */ |
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+#define ITERATIONS 64 |
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+ |
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#ifndef STRLEN |
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/* For builds with no IFUNC support, local calls should be made to internal |
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GLIBC symbol (created by libc_hidden_builtin_def). */ |
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@@ -62,6 +64,8 @@ EALIGN (strstr, 4, 0) |
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cfi_offset(r30, -16) |
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std r29, -24(r1) /* Save callers register r29. */ |
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cfi_offset(r29, -24) |
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+ std r28, -32(r1) /* Save callers register r28. */ |
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+ cfi_offset(r28, -32) |
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std r0, 16(r1) /* Store the link register. */ |
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cfi_offset(lr, 16) |
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stdu r1, -FRAMESIZE(r1) /* Create the stack frame. */ |
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@@ -69,7 +73,6 @@ EALIGN (strstr, 4, 0) |
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dcbt 0, r3 |
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dcbt 0, r4 |
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- |
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cmpdi cr7, r3, 0 |
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beq cr7, L(retnull) |
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cmpdi cr7, r4, 0 |
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@@ -84,10 +87,6 @@ EALIGN (strstr, 4, 0) |
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cmpdi cr7, r3, 0 /* If search str is null. */ |
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beq cr7, L(ret_r3) |
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- /* Call __strstr_ppc if needle len > 2048 */ |
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- cmpdi cr7, r3, 2048 |
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- bgt cr7, L(default) |
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- |
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mr r31, r3 |
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mr r4, r3 |
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mr r3, r29 |
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@@ -105,7 +104,8 @@ EALIGN (strstr, 4, 0) |
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/* If first char of search str is not present. */ |
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cmpdi cr7, r3, 0 |
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ble cr7, L(end) |
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- |
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+ /* Reg r28 is used to count the number of iterations. */ |
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+ li r28, 0 |
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rldicl r8, r3, 0, 52 /* Page cross check. */ |
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cmpldi cr7, r8, 4096-16 |
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bgt cr7, L(bytebybyte) |
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@@ -324,6 +324,10 @@ L(return4): |
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.align 4 |
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L(begin): |
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mr r3, r8 |
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+ /* When our iterations exceed ITERATIONS,fall back to default. */ |
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+ addi r28, r28, 1 |
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+ cmpdi cr7, r28, ITERATIONS |
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+ beq cr7, L(default) |
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lbz r4, 0(r30) |
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bl STRCHR |
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nop |
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@@ -423,6 +427,10 @@ L(nextbyte): |
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cmpdi cr7, r9, -1 |
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beq cr7, L(end) |
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addi r3, r4, 1 |
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+ /* When our iterations exceed ITERATIONS,fall back to default. */ |
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+ addi r28, r28, 1 |
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+ cmpdi cr7, r28, ITERATIONS |
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+ beq cr7, L(default) |
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lbz r4, 0(r30) |
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bl STRCHR |
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nop |
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@@ -490,7 +498,6 @@ L(retnull): |
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.align 4 |
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L(default): |
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- mr r3, r29 |
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mr r4, r30 |
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bl __strstr_ppc |
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nop |
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@@ -500,6 +507,7 @@ L(end): |
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addi r1, r1, FRAMESIZE /* Restore stack pointer. */ |
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cfi_adjust_cfa_offset(-FRAMESIZE) |
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ld r0, 16(r1) /* Restore the saved link register. */ |
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+ ld r28, -32(r1) /* Restore callers save register r28. */ |
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ld r29, -24(r1) /* Restore callers save register r29. */ |
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ld r30, -16(r1) /* Restore callers save register r30. */ |
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ld r31, -8(r1) /* Restore callers save register r31. */ |
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-- |
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2.1.0
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