From: Julian Seward <jseward@acm.org>
Date: Sat, 28 May 2011 17:07:53 +0000 (+0000)
Subject: dispatch-x86-linux.S:
X-Git-Tag: svn/VALGRIND_3_7_0~452
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a131dc867996d9f9a303b818f994dec0578a8a4;p=thirdparty%2Fvalgrind.git

dispatch-x86-linux.S:
   use test-based detection of GSP pointer changes.
   Saves one load per SB.

dispatch-amd64-linux.S:
   ditto

dispatch-amd64-linux.S:
   use movabsq to get &VG_(tt_fast) into a register,
   instead of an rsp-relative load from a constant pool.
   Saves a second load per SB.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11785
---

diff --git a/coregrind/m_dispatch/dispatch-amd64-linux.S b/coregrind/m_dispatch/dispatch-amd64-linux.S
index b125a573fb..82a77bd66a 100644
--- a/coregrind/m_dispatch/dispatch-amd64-linux.S
+++ b/coregrind/m_dispatch/dispatch-amd64-linux.S
@@ -121,12 +121,9 @@ VG_(run_innerloop__dispatch_unprofiled):
 	/* AT ENTRY: %rax is next guest addr, %rbp is possibly
            modified guest state ptr */
 
-	/* Has the guest state pointer been messed with?  If yes, exit.
-           Also, set %rcx to be &VG_(tt_fast), some insns before it is
-           used, in the hope of getting it off the critical path.  This
-           location seems to be optimal on 2.2GHz Athlon64. */
-	cmpq	8(%rsp), %rbp
-	movq	VG_(tt_fast)@GOTPCREL(%rip), %rcx
+	/* Has the guest state pointer been messed with?  If yes,
+	   exit. */
+	testq   $1, %rbp
 	jnz	gsp_changed
 
 	/* save the jump address in the guest state */
@@ -137,6 +134,7 @@ VG_(run_innerloop__dispatch_unprofiled):
 	jz	counter_is_zero
 
 	/* try a fast lookup in the translation cache */
+	movabsq $VG_(tt_fast), %rcx
 	movq	%rax, %rbx		/* next guest addr */
 	andq	$VG_TT_FAST_MASK, %rbx	/* entry# */
 	shlq	$4, %rbx		/* entry# * sizeof(FastCacheEntry) */
@@ -162,12 +160,9 @@ VG_(run_innerloop__dispatch_profiled):
 	/* AT ENTRY: %rax is next guest addr, %rbp is possibly
            modified guest state ptr */
 
-	/* Has the guest state pointer been messed with?  If yes, exit.
-           Also, set %rcx to be &VG_(tt_fast), some insns before it is
-           used, in the hope of getting it off the critical path.  This
-           location seems to be optimal on 2.2GHz Athlon64. */
-	cmpq	8(%rsp), %rbp
-	movq	VG_(tt_fast)@GOTPCREL(%rip), %rcx
+	/* Has the guest state pointer been messed with?  If yes,
+	   exit. */
+	testq   $1, %rbp
 	jnz	gsp_changed
 
 	/* save the jump address in the guest state */
@@ -178,6 +173,7 @@ VG_(run_innerloop__dispatch_profiled):
 	jz	counter_is_zero
 
 	/* try a fast lookup in the translation cache */
+	movabsq $VG_(tt_fast), %rcx
 	movq	%rax, %rbx
 	andq	$VG_TT_FAST_MASK, %rbx	/* entry# */
 	shlq	$4, %rbx		/* entry# * sizeof(FastCacheEntry) */
diff --git a/coregrind/m_dispatch/dispatch-x86-linux.S b/coregrind/m_dispatch/dispatch-x86-linux.S
index 774aa8ae52..c719e010ac 100644
--- a/coregrind/m_dispatch/dispatch-x86-linux.S
+++ b/coregrind/m_dispatch/dispatch-x86-linux.S
@@ -111,7 +111,7 @@ VG_(run_innerloop__dispatch_unprofiled):
            modified guest state ptr */
 
 	/* Has the guest state pointer been messed with?  If yes, exit. */
-	cmpl	28(%esp), %ebp
+	testl	$1, %ebp
 	jnz	gsp_changed
 
 	/* save the jump address in the guest state */
@@ -147,7 +147,7 @@ VG_(run_innerloop__dispatch_profiled):
            modified guest state ptr */
 
 	/* Has the guest state pointer been messed with?  If yes, exit. */
-	cmpl	28(%esp), %ebp
+	testl	$1, %ebp
 	jnz	gsp_changed
 
 	/* save the jump address in the guest state */