[Bug tree-optimization/19633] local address incorrectly thought to escape

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2005-01-30 
20:50 -------
I still see "b" marked as "call clobbered": 
 
struct S { int w, x, y, z; }; 
struct T { int r; struct S s; }; 
 
void bar(struct S, int); 
 
void foo(int a, struct T b) 
{ 
  struct S *c = 0; 
  if (a) 
    c = &b.s; 
  bar (*c, a); 
} 
 
 
--> .alias4 dump 
 
;; Function foo (foo) 
 
Visiting use-def links for 0B 
Visiting use-def links for &bD.1459.sD.1454 
foo: Total number of aliased vops: 1 
 
Referenced variables in foo: 4 
 
Variable: cD.1462, UID 0, struct S *, type memory tag: TMT.0D.1469 
 
Variable: aD.1458, UID 1, intD.0, default def: aD.1458_3 
 
Variable: bD.1459, UID 2, struct T, is an alias tag, is addressable, call 
clobbered, default def: bD.1459_5 
 
Variable: TMT.0D.1469, UID 3, struct S, is addressable, is global, call 
clobbered, may aliases: { bD.1459 } 
 
(...) 
 
Aliased symbols 
 
bD.1459, UID 2, struct T, is an alias tag, is addressable, call clobbered, 
default def: bD.1459_5 
TMT.0D.1469, UID 3, struct S, is addressable, is global, call clobbered, may 
aliases: { bD.1459 } 
 
Dereferenced pointers 
 
cD.1462, UID 0, struct S *, type memory tag: TMT.0D.1469 
 
Type memory tags 
 
TMT.0D.1469, UID 3, struct S, is addressable, is global, call clobbered, may 
aliases: { bD.1459 } 
 
(...) 
 
foo (aD.1458, bD.1459) 
{ 
  struct S * cD.1462; 
 
  # BLOCK 0 
  # PRED: ENTRY [100.0%]  (fallthru,exec) 
  if (aD.1458_3 != 0) goto <L0>; else goto <L1>; 
  # SUCC: 1 [67.0%]  (true,exec) 2 [33.0%]  (false,exec) 
 
  # BLOCK 1 
  # PRED: 0 [67.0%]  (true,exec) 
<L0>:; 
  # SUCC: 2 [100.0%]  (fallthru,exec) 
 
  # BLOCK 2 
  # PRED: 0 [33.0%]  (false,exec) 1 [100.0%]  (fallthru,exec) 
  # cD.1462_1 = PHI <0B(0), &bD.1459.sD.1454(1)>; 
<L1>:; 
  #   bD.1459_6 = V_MAY_DEF <bD.1459_5>; 
  bar (*cD.1462_1, aD.1458_3); 
  return; 
  # SUCC: EXIT [100.0%] 
 
} 
 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19633