Micro-optimize PUSHW/PUSHB

* src/sfnt.c (CHECK_STACK_AVAILABLE): New macro.
(PUSH):
(PUSH_UNCHECKED): Always define to unchecked versions,
even if TEST.
(PUSH2_UNCHECKED): New macro.
(NPUSHB):
(NPUSHW):
(PUSHB):
(PUSHW): Check the number of remaining stack elements
once.
(stack_overflow_test_args): Expect zero stack arguments.

1 files changed, 37 insertions, 14 deletions

diff --git a/src/sfnt.c b/src/sfnt.c
index 3f1639b3734..876db70bcda 100644
--- a/src/sfnt.c
+++ b/src/sfnt.c
@@ -5708,6 +5708,17 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
       TRAP ("stack underflow");                 \
   }
 
+#define CHECK_STACK_AVAILABLE(n)                \
+  {                                             \
+    char *stack_end;                            \
+                                                \
+    stack_end                                   \
+      = (char *) interpreter->twilight_x;       \
+    if (((char *) (interpreter->SP + (n))       \
+         > stack_end))                          \
+      TRAP ("stack overflow");                  \
+  }
+
 #define CHECK_PREP()                            \
   if (!is_prep)                                 \
     TRAP ("instruction executed not valid"      \
@@ -5756,7 +5767,7 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
    ? (TRAP ("stack underflow"), 0)              \
    : *(interpreter->SP - 1))
 
-#ifndef TEST
+#if !defined TEST || !0
 
 #define PUSH(value)                             \
   {                                             \
@@ -5774,7 +5785,7 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
     interpreter->SP++;                          \
   }
 
-#else
+#else /* TEST && 0 */
 
 #define PUSH(value)                             \
   {                                             \
@@ -5792,12 +5803,14 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
 
 #define PUSH_UNCHECKED(value) PUSH (value)
 
-#endif
+#endif /* TEST && 0 */
 
-#define PUSH2(high, low)                        \
+#define PUSH2_UNCHECKED(high, low)              \
   {                                             \
-    PUSH ((int16_t) ((int8_t) high) << 8        \
-          | low);                               \
+    int16_t word;                               \
+                                                \
+    word = (((int8_t) high) << 8 | low);        \
+    PUSH_UNCHECKED (word);                      \
   }                                             \
 
 #define SRP0()                                  \
@@ -6097,6 +6110,7 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
 #define NPUSHB()                                \
   {                                             \
     int b, nbytes, IP;                          \
+    unsigned char *ip;                          \
                                                 \
     if ((IP = interpreter->IP + 1)              \
         >= interpreter->num_instructions)       \
@@ -6109,8 +6123,10 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
         > interpreter->num_instructions)        \
       TRAP ("args to NPUSHB lie outside IS");   \
                                                 \
+    CHECK_STACK_AVAILABLE (nbytes);             \
+    ip = interpreter->instructions;             \
     for (b = IP + 1; b < IP + 1 + nbytes; ++b)  \
-      PUSH (interpreter->instructions[b]);      \
+      PUSH_UNCHECKED (ip[b]);                   \
                                                 \
     interpreter->IP += nbytes + 1;              \
   }
@@ -6118,6 +6134,7 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
 #define NPUSHW()                                \
   {                                             \
     int b, nbytes, IP;                          \
+    unsigned char *ip;                          \
                                                 \
     if ((IP = interpreter->IP + 1)              \
         >= interpreter->num_instructions)       \
@@ -6130,10 +6147,11 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
         > interpreter->num_instructions)        \
       TRAP ("args to NPUSHW lie outside IS");   \
                                                 \
+    CHECK_STACK_AVAILABLE (nbytes / 2);         \
+    ip = interpreter->instructions;             \
     for (b = IP + 1; b < IP + 1 + nbytes;       \
          b += 2)                                \
-      PUSH2 (interpreter->instructions[b],      \
-             interpreter->instructions[b + 1]); \
+      PUSH2_UNCHECKED (ip[b], ip[b + 1]);       \
                                                 \
     interpreter->IP += nbytes + 1;              \
   }
@@ -6634,6 +6652,7 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
 #define PUSHB()                                 \
   {                                             \
     int b, nbytes, IP;                          \
+    unsigned char *ip;                          \
                                                 \
     IP = interpreter->IP;                       \
     nbytes = opcode - 0xb0 + 1;                 \
@@ -6642,8 +6661,10 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
         > interpreter->num_instructions)        \
       TRAP ("args to PUSHB lie outside IS");    \
                                                 \
+    CHECK_STACK_AVAILABLE (nbytes);             \
+    ip = interpreter->instructions;             \
     for (b = IP + 1; b < IP + nbytes + 1; ++b)  \
-      PUSH (interpreter->instructions[b]);      \
+      PUSH_UNCHECKED (ip[b]);                   \
                                                 \
     interpreter->IP += nbytes;                  \
   }
@@ -6651,6 +6672,7 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
 #define PUSHW()                                 \
   {                                             \
     int b, nbytes, IP;                          \
+    unsigned char *ip;                          \
                                                 \
     IP = interpreter->IP;                       \
     nbytes = (opcode - 0xb8 + 1) * 2;           \
@@ -6659,10 +6681,11 @@ sfnt_interpret_trap (struct sfnt_interpreter *interpreter,
         > interpreter->num_instructions)        \
       TRAP ("args to PUSHW lie outside IS");    \
                                                 \
+    CHECK_STACK_AVAILABLE (nbytes / 2);         \
+    ip = interpreter->instructions;             \
     for (b = IP + 1; b < IP + nbytes + 1;       \
          b += 2)                                \
-      PUSH2 (interpreter->instructions[b],      \
-             interpreter->instructions[b + 1]); \
+      PUSH2_UNCHECKED (ip[b], ip[b + 1]);       \
                                                 \
     interpreter->IP += nbytes;                  \
   }
@@ -16080,8 +16103,8 @@ static struct sfnt_generic_test_args pushw_test_args =
 
 static struct sfnt_generic_test_args stack_overflow_test_args =
   {
-    (uint32_t[100]) { },
-    100,
+    (uint32_t[]) { },
+    0,
     true,
     0,
   };