diff options
-rw-r--r-- | cparser/StructReturn.ml | 14 | ||||
-rw-r--r-- | test/regression/Makefile | 2 | ||||
-rw-r--r-- | test/regression/Results/struct12 | 0 | ||||
-rw-r--r-- | test/regression/struct12.c | 39 |
4 files changed, 50 insertions, 5 deletions
diff --git a/cparser/StructReturn.ml b/cparser/StructReturn.ml index 660f1d9b..5e5602f3 100644 --- a/cparser/StructReturn.ml +++ b/cparser/StructReturn.ml @@ -299,10 +299,15 @@ let rec transf_expr env ctx e = transf_call env ctx None fn args e.etyp (* Function calls returning a composite by reference: add first argument. - ctx = Effects: lv = f(...) -> f(&lv, ...) [copy optimization] + ctx = Effects: lv = f(...) -> f(&newtemp, ...), lv = newtemp f(...) -> f(&newtemp, ...) ctx = Val: lv = f(...) -> f(&newtemp, ...), lv = newtemp f(...) -> f(&newtemp, ...), newtemp + + We used to do a copy optimization: + ctx = Effects: lv = f(...) -> f(&lv, ...) + but it is not correct in case of overlap (see test/regression/struct12.c) + Function calls returning a composite by value: ctx = Effects: lv = f(...) -> newtemp = f(...), lv = newtemp f(...) -> f(...) @@ -332,13 +337,14 @@ and transf_call env ctx opt_lhs fn args ty = | Effects, None -> let tmp = new_temp ~name:"_res" ty in {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []} - | Effects, Some lhs -> - {edesc = ECall(fn', eaddrof lhs :: args'); etyp = TVoid []} + (* Copy optimization, turned off as explained above *) + (* | Effects, Some lhs -> + {edesc = ECall(fn', eaddrof lhs :: args'); etyp = TVoid []} *) | Val, None -> let tmp = new_temp ~name:"_res" ty in ecomma {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []} tmp - | Val, Some lhs -> + | _, Some lhs -> let tmp = new_temp ~name:"_res" ty in ecomma {edesc = ECall(fn', eaddrof tmp :: args'); etyp = TVoid []} (eassign lhs tmp) diff --git a/test/regression/Makefile b/test/regression/Makefile index da7d5755..e2d94aa9 100644 --- a/test/regression/Makefile +++ b/test/regression/Makefile @@ -15,7 +15,7 @@ LIBS=$(LIBMATH) TESTS=int32 int64 floats floats-basics \ expr1 expr6 funptr2 initializers initializers2 initializers3 \ volatile1 volatile2 volatile3 \ - funct3 expr5 struct7 struct8 struct11 casts1 casts2 char1 \ + funct3 expr5 struct7 struct8 struct11 struct12 casts1 casts2 char1 \ sizeof1 sizeof2 binops bool for1 switch switch2 compound \ decl1 interop1 bitfields9 ptrs3 diff --git a/test/regression/Results/struct12 b/test/regression/Results/struct12 new file mode 100644 index 00000000..e69de29b --- /dev/null +++ b/test/regression/Results/struct12 diff --git a/test/regression/struct12.c b/test/regression/struct12.c new file mode 100644 index 00000000..39e62b28 --- /dev/null +++ b/test/regression/struct12.c @@ -0,0 +1,39 @@ +/* This is was originally a regression test for bug 43784 of gcc. + See ISO/IEC 9899:TC3 ยง6.8.6.4p4 and footnote 139. */ + +#include <stdio.h> + +struct s { + unsigned char a[256]; +}; +union u { + struct { struct s b; int c; } d; + struct { int c; struct s b; } e; +}; + +static union u v; +static struct s *p = &v.d.b; +static struct s *q = &v.e.b; + +static struct s __attribute__((noinline)) rp(void) +{ + return *p; +} + +static void qp(void) +{ + *q = rp(); +} + +int main() +{ + int i; + for (i = 0; i < 256; i++) + p->a[i] = i; + qp(); + for (i = 0; i < 256; i++) + if (q->a[i] != i) + printf("ERROR at %d: %d\n", i, q->a[i]); + return 0; +} + |