[68]l: fix off by one instruction in dwarf frame unwinding.

R=rsc
CC=golang-dev
https://golang.org/cl/2543043

diff --git a/src/cmd/ld/dwarf.c b/src/cmd/ld/dwarf.c
index 4b8668d682252e963ee358bae89407cb9e7a2ac7..1e7c35e47e3446c1f49da2a3dbef9d36c0007db1 100644 (file)
--- a/src/cmd/ld/dwarf.c
+++ b/src/cmd/ld/dwarf.c
@@ -747,10 +747,11 @@ writelines(void)
                        diag("reachable code before seeing any history: %P", p);
                        continue;
                }
-               
+
                dwinfo->child = newdie(dwinfo->child, DW_ABRV_FUNCTION);
                newattr(dwinfo->child, DW_AT_name, DW_CLS_STRING, strlen(s->name), s->name);
-               newattr(dwinfo->child, DW_AT_low_pc, DW_CLS_ADDRESS, p->pc, 0);
+               newattr(dwinfo->child, DW_AT_low_pc, DW_CLS_ADDRESS, s->text->pc, 0);
+               newattr(dwinfo->child, DW_AT_high_pc, DW_CLS_ADDRESS, s->text->pc + s->size, 0);
 
                for(q = p; q != P && (q == p || q->as != ATEXT); q = q->link) {
                        epc = q->pc;
@@ -780,9 +781,6 @@ writelines(void)
                        lc  = q->line;
                        llc = lline;
                }
-
-               newattr(dwinfo->child, DW_AT_high_pc, DW_CLS_ADDRESS, epc+1, 0);
-
        }
 
        flushunit(epc, unitstart);
@@ -795,8 +793,8 @@ writelines(void)
 enum
 {
        CIERESERVE = 16,
-       DATAALIGNMENTFACTOR = -4,
-       FAKERETURNCOLUMN = 16
+       DATAALIGNMENTFACTOR = -4,       // TODO -PtrSize?
+       FAKERETURNCOLUMN = 16           // TODO gdb6 doesnt like > 15?
 };
 
 static void
@@ -824,7 +822,7 @@ writeframes(void)
 {
        Prog *p, *q;
        Sym *s;
-       vlong fdeo, fdesize, pad, cfa, pc, epc;
+       vlong fdeo, fdesize, pad, cfa, pc;
 
        frameo = cpos();
 
@@ -867,16 +865,14 @@ writeframes(void)
                cfa = PtrSize;  // CFA starts at sp+PtrSize
                p = s->text;
                pc = p->pc;
-               epc = p->pc;
 
-               for(q = p; q != P; q = q->link) {
-                       epc = q->pc;
+               for(q = p; q->link != P; q = q->link) {
                        if (q->spadj == 0)
                                continue;
 
                        cfa += q->spadj;
-                       putpccfadelta(q->pc - pc, cfa);
-                       pc = q->pc;
+                       putpccfadelta(q->link->pc - pc, cfa);
+                       pc = q->link->pc;
                }
 
                fdesize = cpos() - fdeo - 4;    // exclude the length field.
@@ -890,7 +886,7 @@ writeframes(void)
                LPUT(fdesize);
                LPUT(0);
                addrput(p->pc);
-               addrput(epc - p->pc);
+               addrput(s->size);
 
                cflush();
                seek(cout, fdeo + 4 + fdesize, 0);