From: Stefan Ring <stefan@complang.tuwien.ac.at>
Date: Mon, 6 Jul 2009 15:16:20 +0000 (+0200)
Subject: i386 / x86_64: Align patcher trap instruction.
X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=cacao.git;a=commitdiff_plain;h=d972621e13e95b7ac0160902af800f2a745ae7c0

i386 / x86_64: Align patcher trap instruction.
* src/vm/jit/i386/emit.c: Added emit_patcher_alignment.
* src/vm/jit/x86_64/emit.c: Likewise.
* src/vm/jit/i386/md-trap.h: Added emit_patcher_alignment, defined
ALIGN_PATCHER_TRAP.
* src/vm/jit/x86_64/md-trap.h: Likewise.
* src/vm/jit/patcher-common.cpp (patcher_add_patch_ref): Use
emit_patcher_alignment if requested.
---

diff --git a/src/vm/jit/i386/emit.c b/src/vm/jit/i386/emit.c
index dfc62a78b..cfddc22a7 100644
--- a/src/vm/jit/i386/emit.c
+++ b/src/vm/jit/i386/emit.c
@@ -537,6 +537,19 @@ void emit_trap_countdown(codegendata *cd, s4 *counter)
 	M_ALD_MEM(REG_METHODPTR, TRAP_COUNTDOWN);
 }
 
+/* emit_patcher_alignment ******************************************************
+
+   Emit NOP to ensure placement at an even address.
+
+*******************************************************************************/
+
+void emit_patcher_alignment(codegendata *cd)
+{
+	if ((uintptr_t) cd->mcodeptr & 1)
+		M_NOP;
+}
+
+
 /* emit_trap *******************************************************************
 
    Emit a trap instruction and return the original machine code.
diff --git a/src/vm/jit/i386/md-trap.h b/src/vm/jit/i386/md-trap.h
index 6cf2bbf20..d8bfecbe3 100644
--- a/src/vm/jit/i386/md-trap.h
+++ b/src/vm/jit/i386/md-trap.h
@@ -80,6 +80,13 @@ enum {
 		(xpc) = (void*) (((uintptr_t) (ra)) - 2); \
 	} while(0)
 
+/**
+ * Align traps so they don't cross cache line boundaries.
+ */
+ 
+#define ALIGN_PATCHER_TRAP
+
+void emit_patcher_alignment(codegendata *cd);
 
 #endif /* _MD_TRAP_H */
 
diff --git a/src/vm/jit/patcher-common.cpp b/src/vm/jit/patcher-common.cpp
index 8d3e6dcef..c96f14808 100644
--- a/src/vm/jit/patcher-common.cpp
+++ b/src/vm/jit/patcher-common.cpp
@@ -34,6 +34,7 @@
 
 #include "codegen.h"                   /* for PATCHER_NOPS */
 #include "md.h"
+#include "trap.hpp"
 
 #include "mm/memory.hpp"
 
@@ -175,6 +176,11 @@ void patcher_add_patch_ref(jitdata *jd, functionptr patcher, void* ref, s4 disp)
 	code     = jd->code;
 	patchmpc = cd->mcodeptr - cd->mcodebase;
 
+#if defined(ALIGN_PATCHER_TRAP)
+	emit_patcher_alignment(cd);
+	patchmpc = cd->mcodeptr - cd->mcodebase;
+#endif
+
 #if !defined(NDEBUG)
 	if (patcher_list_find(code, (void*) (intptr_t) patchmpc) != NULL)
 		vm_abort("patcher_add_patch_ref: different patchers at same position.");
diff --git a/src/vm/jit/x86_64/emit.c b/src/vm/jit/x86_64/emit.c
index 79cd94dd6..398d7d058 100644
--- a/src/vm/jit/x86_64/emit.c
+++ b/src/vm/jit/x86_64/emit.c
@@ -424,6 +424,19 @@ void emit_trap_compiler(codegendata *cd)
 }
 
 
+/* emit_patcher_alignment ******************************************************
+
+   Emit NOP to ensure placement at an even address.
+
+*******************************************************************************/
+
+void emit_patcher_alignment(codegendata *cd)
+{
+	if ((uintptr_t) cd->mcodeptr & 1)
+		M_NOP;
+}
+
+
 /* emit_trap *******************************************************************
 
    Emit a trap instruction and return the original machine code.
diff --git a/src/vm/jit/x86_64/md-trap.h b/src/vm/jit/x86_64/md-trap.h
index 8b09e3c6e..c8d538332 100644
--- a/src/vm/jit/x86_64/md-trap.h
+++ b/src/vm/jit/x86_64/md-trap.h
@@ -81,6 +81,14 @@ enum {
 	} while(0)
 
 
+/**
+ * Align traps so they don't cross cache line boundaries.
+ */
+ 
+#define ALIGN_PATCHER_TRAP
+
+void emit_patcher_alignment(codegendata *cd);
+
 #endif /* _MD_TRAP_H */