From: Chris Hanson <org/chris-hanson/cph>
Date: Tue, 17 Sep 2019 06:50:23 +0000 (-0700)
Subject: Workaround for inexplicable fatal error on macOS.
X-Git-Tag: mit-scheme-pucked-10.1.20~11^2~49
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=689da8bf97534063f1800caf544a694de81d511e;p=mit-scheme.git

Workaround for inexplicable fatal error on macOS.
---

diff --git a/src/microcode/cmpintmd/x86-64.c b/src/microcode/cmpintmd/x86-64.c
index 84b9f6214..8edfd8baa 100644
--- a/src/microcode/cmpintmd/x86-64.c
+++ b/src/microcode/cmpintmd/x86-64.c
@@ -224,24 +224,26 @@ write_uuo_target (insn_t * target, SCHEME_OBJECT * saddr)
      But if the target is a compiled closure pointing into a block
      somewhere else, the block may not have been relocated yet and so
      we don't know where the PC will be in the newspace.  */
-  if ((((int64_t *) (newspace_to_tospace (target)))[-1]) == 0)
-    {
-      ptrdiff_t jmprel32_offset = (target - (&addr[15]));
-      if ((INT32_MIN <= jmprel32_offset) && (jmprel32_offset <= INT32_MAX))
-	{
-	  (addr[10]) = 0xe9;	/* JMP rel32 */
-	  (* ((int32_t *) (&addr[11]))) = jmprel32_offset;
-	}
-      else
-	{
-	  (addr[10]) = 0x48;	/* MOV RAX,imm64 */
-	  (addr[11]) = 0xb8;
-	  (* ((insn_t **) (&addr[12]))) = target;
-	  (addr[20]) = 0xff;	/* JMP RAX */
-	  (addr[21]) = 0xe0;
-	}
-    }
-  else
+
+  // **** For unknown reasons this optimization doesn't work right on macOS.
+  // if ((((int64_t *) (newspace_to_tospace (target)))[-1]) == 0)
+  //   {
+  //     ptrdiff_t jmprel32_offset = (target - (&addr[15]));
+  //     if ((INT32_MIN <= jmprel32_offset) && (jmprel32_offset <= INT32_MAX))
+  // 	{
+  // 	  (addr[10]) = 0xe9;	/* JMP rel32 */
+  // 	  (* ((int32_t *) (&addr[11]))) = jmprel32_offset;
+  // 	}
+  //     else
+  // 	{
+  // 	  (addr[10]) = 0x48;	/* MOV RAX,imm64 */
+  // 	  (addr[11]) = 0xb8;
+  // 	  (* ((insn_t **) (&addr[12]))) = target;
+  // 	  (addr[20]) = 0xff;	/* JMP RAX */
+  // 	  (addr[21]) = 0xe0;
+  // 	}
+  //   }
+  // else
     {
       (addr[10]) = 0x48;	/* MOV RAX,-8(RCX) */
       (addr[11]) = 0x8b;