Format_auto_header test needs to cope with larger header sizes (not just 8!)

Copied from Perforce
 Change: 24156
 ServerID: perforce.ravenbrook.com

3 files changed, 33 insertions, 42 deletions

diff --git a/mps/code/amcsshe.c b/mps/code/amcsshe.c
index 778ce7c1710..5c5c5edff0f 100644
--- a/mps/code/amcsshe.c
+++ b/mps/code/amcsshe.c
@@ -153,7 +153,7 @@ static mps_addr_t make(void)
     res = init(userP, size, exactRoots, exactRootsCOUNT);
     if (res)
       die(res, "dylan_init");
-    ((int*)p)[0] = realTYPE;
+    ((int*)p)[0] = realHeader;
     ((int*)p)[1] = 0xED0ED;
   } while(!mps_commit(ap, p, size + headerSIZE));
 
diff --git a/mps/code/fmthe.c b/mps/code/fmthe.c
index 148c37d5c10..3455b30cc80 100644
--- a/mps/code/fmthe.c
+++ b/mps/code/fmthe.c
@@ -288,21 +288,23 @@ static mps_res_t dylan_scan1(mps_ss_t mps_ss, mps_addr_t *object_io)
   unsigned es;          /* variable part element size (log2 of bits) */
   mps_word_t vt;        /* total vector length */
   mps_res_t res;
-  int* header;
+  int header;
 
   assert(object_io != NULL);
 
   p = (mps_addr_t *)*object_io;
   assert(p != NULL);
 
-  header = (int*)((char*)p - headerSIZE);
-  if (*header != realTYPE) {
-    switch (*header) {
-    case pad1TYPE: *object_io = (mps_addr_t)((char*)p + 4); break;
-    case pad2TYPE: *object_io = (mps_addr_t)((char*)p + 8); break;
-    default: notreached(); break;
-    }
-    return MPS_RES_OK;
+  header = *(int*)((char*)p - headerSIZE);
+  switch(headerType(header)) {
+  case realTYPE:
+      break;
+  case padTYPE:
+      *object_io = (mps_addr_t)((char*)p + headerPadSize(header));
+      return MPS_RES_OK;
+  default:
+      notreached();
+      break;
   }
 
   h = (mps_word_t)p[0];         /* load the header word */
@@ -458,18 +460,20 @@ static mps_addr_t dylan_skip(mps_addr_t object)
   mps_word_t vt;        /* total vector length */
   unsigned vb;          /* vector bias */
   unsigned es;          /* variable part element size (log2 of bits) */
-  int* header;
+  int header;
 
   p = (mps_addr_t *)object;
   assert(p != NULL);
 
-  header = (int*)((char*)object - headerSIZE);
-  if (*header != realTYPE) {
-    switch (*header) {
-    case pad1TYPE: return (mps_addr_t)((char*)object + 4); break;
-    case pad2TYPE: return (mps_addr_t)((char*)object + 8); break;
-    default: assert(0 == 1); break;
-    }
+  header = *(int*)((char*)object - headerSIZE);
+  switch(headerType(header)) {
+  case realTYPE:
+      break;
+  case padTYPE:
+      return (mps_addr_t)((char*)object + headerPadSize(header));
+  default:
+      notreached();
+      break;
   }
 
   h = (mps_word_t)p[0];         /* load the header word */
@@ -519,12 +523,11 @@ static mps_addr_t dylan_skip(mps_addr_t object)
 static mps_addr_t dylan_isfwd(mps_addr_t object)
 {
   mps_word_t h, tag;
-  int *header;
+  int header;
 
-  header = (int*)((char*)object - headerSIZE);
-  if (*header != realTYPE) {
+  header = *(int*)((char*)object - headerSIZE);
+  if (headerType(header) != realTYPE)
     return NULL;
-  }
 
   h = *(mps_word_t *)object;
   tag = h & 3;
@@ -556,22 +559,7 @@ static void dylan_fwd(mps_addr_t old, mps_addr_t new)
 
 static void dylan_pad(mps_addr_t addr, size_t fullSize)
 {
-  mps_word_t *p;
-  size_t size;
-
-  p = (mps_word_t *)AddHeader(addr);
-  size = fullSize - headerSIZE;
-  if (fullSize <= headerSIZE) {
-    *(int*)addr = (fullSize == 4) ? pad1TYPE : pad2TYPE;
-  } else {
-    *(int*)addr = realTYPE;
-    if(size == sizeof(mps_word_t))        /* single-word object? */
-      p[0] = 1;
-    else {
-      p[0] = 2;
-      p[1] = (mps_word_t)AddHeader((char *)addr + fullSize);
-    }
-  }
+  *(int*)addr = padHeader(fullSize);
 }
 
 
diff --git a/mps/code/fmthe.h b/mps/code/fmthe.h
index 58bbe03f7b8..174ab24c5a8 100644
--- a/mps/code/fmthe.h
+++ b/mps/code/fmthe.h
@@ -29,10 +29,13 @@ extern mps_res_t HeaderFormatCheck(mps_addr_t addr);
 #define ALIGN sizeof(mps_word_t)    /* alignment for Dylan format */
 
 
-#define headerSIZE (8)
+#define headerSIZE (32)
+#define headerTypeBits 1
 #define realTYPE 0
-#define pad1TYPE 1
-#define pad2TYPE 2
-
+#define realHeader realTYPE
+#define padTYPE  1
+#define headerType(header) ((header) & ((1 << headerTypeBits) - 1))
+#define headerPadSize(header) ((header) >> headerTypeBits)
+#define padHeader(size) ((size << headerTypeBits) | padTYPE)
 
 #endif /* fmthe_h */