From ddd6395a50e33a34b42c39add3d6b621fdd08b72 Mon Sep 17 00:00:00 2001
From: Matt Birkholz <matt@birkholz.chandler.az.us>
Date: Wed, 7 Mar 2012 21:06:24 -0700
Subject: [PATCH] svm: Remove setjmp from execute_instruction.

Trade some debuggability for significantly better performance.
---
 src/microcode/svm1-interp.c | 51 ++++++++++++-------------------------
 1 file changed, 16 insertions(+), 35 deletions(-)

diff --git a/src/microcode/svm1-interp.c b/src/microcode/svm1-interp.c
index 72a236c8c..c20a174f2 100644
--- a/src/microcode/svm1-interp.c
+++ b/src/microcode/svm1-interp.c
@@ -30,8 +30,6 @@ USA.
 #include "fixnum.h"
 #include "svm1-defns.h"
 #include "cmpintmd/svm1.h"
-
-#define SVM1_REG_SP 0
 
 typedef SCHEME_OBJECT word_t;	/* convenience abbreviation */
 
@@ -145,14 +143,11 @@ static trap_3_t * traps_3 [256];
 #define DECODE_TRAP_2(name) byte_t name = NEXT_BYTE
 #define DECODE_TRAP_3(name) byte_t name = NEXT_BYTE
 
-static void signal_illegal_instruction (void);
 static void initialize_decoder_tables (void);
 
 static int initialized_p = 0;
 static int little_endian_p;
 
-static bool execute_instruction (void);
-
 static void
 compute_little_endian_p (void)
 {
@@ -206,33 +201,16 @@ C_to_interface (void * address)
 {
   IMPORT_REGS ();
   PC = address;
-  while (execute_instruction ());
+  while ((* (inst_defns[NEXT_BYTE])) ());
   EXPORT_REGS ();
   return (svm1_result);
 }
 
-static jmp_buf k_execute_instruction;
-
-static bool
-execute_instruction (void)
-{
-  if ((setjmp (k_execute_instruction)) != 0)
-    return (0);
-  return ((* (inst_defns[NEXT_BYTE])) ());
-}
-
 static bool
 illegal_instruction (void)
-{
-  signal_illegal_instruction ();
-  return (0);
-}
-
-static void
-signal_illegal_instruction (void)
 {
   svm1_result = ERR_COMPILED_CODE_ERROR;
-  longjmp (k_execute_instruction, 1);
+  return (0);
 }
 
 #define TO_SIGNED(n) ((long) (n))
@@ -279,8 +257,7 @@ static wreg_t
 decode_wreg (void)
 {
   byte_t b = NEXT_BYTE;
-  if (!WORD_REGISTER_P (b))
-    signal_illegal_instruction ();
+  assert (WORD_REGISTER_P (b));
   return (b);
 }
 
@@ -288,8 +265,7 @@ static freg_t
 decode_freg (void)
 {
   byte_t b = NEXT_BYTE;
-  if (!FLOAT_REGISTER_P (b))
-    signal_illegal_instruction ();
+  assert (FLOAT_REGISTER_P (b));
   return (b);
 }
 
@@ -297,8 +273,7 @@ static tc_t
 decode_type_word (void)
 {
   byte_t b = NEXT_BYTE;
-  if (b >= N_TYPE_CODES)
-    signal_illegal_instruction ();
+  assert (b < N_TYPE_CODES);
   return (b);
 }
 
@@ -775,7 +750,7 @@ DEFINE_INST (trap_trap_0)
 static bool
 illegal_trap_0 (void)
 {
-  signal_illegal_instruction ();
+  svm1_result = ERR_COMPILED_CODE_ERROR;
   return (0);
 }
 
@@ -788,7 +763,7 @@ DEFINE_INST (trap_trap_1_wr)
 static bool
 illegal_trap_1 (wreg_t r1)
 {
-  signal_illegal_instruction ();
+  svm1_result = ERR_COMPILED_CODE_ERROR;
   return (0);
 }
 
@@ -801,7 +776,7 @@ DEFINE_INST (trap_trap_2_wr)
 static bool
 illegal_trap_2 (wreg_t r1, wreg_t r2)
 {
-  signal_illegal_instruction ();
+  svm1_result = ERR_COMPILED_CODE_ERROR;
   return (0);
 }
 
@@ -814,7 +789,7 @@ DEFINE_INST (trap_trap_3_wr)
 static bool
 illegal_trap_3 (wreg_t r1, wreg_t r2, wreg_t r3)
 {
-  signal_illegal_instruction ();
+  svm1_result = ERR_COMPILED_CODE_ERROR;
   return (0);
 }
 
@@ -1242,10 +1217,16 @@ decode_address (address_t * address)
   (* (address_decoders[NEXT_BYTE])) (address);
 }
 
+static word_t
+illegal_address_value (address_t * address)
+{
+  return (0);
+}
+
 static void
 illegal_address (address_t * address)
 {
-  signal_illegal_instruction ();
+  address->value = illegal_address_value;
 }
 
 static word_t
-- 
2.25.1