[PATCH v3 3/7] amd64_analyze_prologue: merge op and buf

[Victor Collod <vcollod@nvidia.com>]

Both variables were used to store function code.

2020-06-23  Victor Collod  <vcollod@nvidia.com>

	* amd64-tdep.c (amd64_analyze_prologue): Merge op and buf.
---
 gdb/amd64-tdep.c | 28 +++++++++++-----------------
 1 file changed, 11 insertions(+), 17 deletions(-)

diff --git a/gdb/amd64-tdep.c b/gdb/amd64-tdep.c
index ff12cb874b8..c1a9b553e20 100644
--- a/gdb/amd64-tdep.c
+++ b/gdb/amd64-tdep.c
@@ -2374,7 +2374,6 @@ amd64_analyze_prologue (struct gdbarch *gdbarch,
 			CORE_ADDR pc, CORE_ADDR current_pc,
 			struct amd64_frame_cache *cache)
 {
-  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
   /* The `endbr64` instruction.  */
   static const gdb_byte endbr64[4] = { 0xf3, 0x0f, 0x1e, 0xfa };
   /* There are two variations of movq %rsp, %rbp.  */
@@ -2384,8 +2383,7 @@ amd64_analyze_prologue (struct gdbarch *gdbarch,
   static const gdb_byte mov_esp_ebp_1[2] = { 0x89, 0xe5 };
   static const gdb_byte mov_esp_ebp_2[2] = { 0x8b, 0xec };
 
-  gdb_byte buf[3];
-  gdb_byte op;
+  gdb_byte buf[4];
 
   /* Analysis must not go past current_pc.  */
   if (pc >= current_pc)
@@ -2396,24 +2394,20 @@ amd64_analyze_prologue (struct gdbarch *gdbarch,
   else
     pc = amd64_analyze_stack_align (pc, current_pc, cache);
 
-  op = read_code_unsigned_integer (pc, 1, byte_order);
-
-  /* Check for the `endbr64` instruction, skip it if found.  */
-  if (op == endbr64[0])
+  read_code (pc, buf, 4);
+  /* Check for the `endbr64' instruction and skip it if found.  */
+  if (memcmp (buf, endbr64, sizeof (endbr64)) == 0)
     {
-      read_code (pc + 1, buf, 3);
-
-      if (memcmp (buf, &endbr64[1], 3) == 0)
-	pc += 4;
+      pc += sizeof (endbr64);
+      /* If we went past the allowed bound, stop.  */
+      if (pc >= current_pc)
+	return current_pc;
 
-      op = read_code_unsigned_integer (pc, 1, byte_order);
+      /* Update the code buffer, as pc changed.  */
+      read_code (pc, buf, 1);
     }
 
-  /* If we went past the allowed bound, stop.  */
-  if (pc >= current_pc)
-    return current_pc;
-
-  if (op == 0x55)		/* pushq %rbp */
+  if (buf[0] == 0x55)           /* pushq %rbp */
     {
       /* Take into account that we've executed the `pushq %rbp' that
          starts this instruction sequence.  */
-- 
2.20.1