| Message ID | 46673e65-eefd-68d5-088b-1a9723a84a9c@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | correct the representation of ADDR_EXPR involving pointer to array [PR 90694] | expand |
On 5/31/19 1:56 PM, Martin Sebor wrote: > Given a poiner to array p, tree dumps for expressions like &(*p)[2] > actually show &*p[2]. That's not right -- the parentheses are > important to differentiate indexing into the array the pointer > points to from indexing into the pointer. > > The attached patch adjusts the tree pretty printer to add the parens > when the pointer points to an array. > > Tested on x86_64-linux. > > Martin > > gcc-90694.diff > > PR middle-end/90694 - incorrect representation of ADDR_EXPR involving a pointer to array > > gcc/ChangeLog: > > PR middle-end/90694 > * tree-pretty-print.c (dump_generic_node): Add parentheses. > > gcc/testsuite/ChangeLog: > > PR middle-end/90694 > * gcc.dg/tree-ssa/dump-5.c: New test. OK. I'm going to assume that the gimple parser already does the right thing since it's supposed to already handle C expressions correctly. Jeff
On Fri, May 31, 2019 at 10:50 PM Jeff Law <law@redhat.com> wrote: > > On 5/31/19 1:56 PM, Martin Sebor wrote: > > Given a poiner to array p, tree dumps for expressions like &(*p)[2] > > actually show &*p[2]. That's not right -- the parentheses are > > important to differentiate indexing into the array the pointer > > points to from indexing into the pointer. > > > > The attached patch adjusts the tree pretty printer to add the parens > > when the pointer points to an array. > > > > Tested on x86_64-linux. > > > > Martin > > > > gcc-90694.diff > > > > PR middle-end/90694 - incorrect representation of ADDR_EXPR involving a pointer to array > > > > gcc/ChangeLog: > > > > PR middle-end/90694 > > * tree-pretty-print.c (dump_generic_node): Add parentheses. > > > > gcc/testsuite/ChangeLog: > > > > PR middle-end/90694 > > * gcc.dg/tree-ssa/dump-5.c: New test. > OK. I'm going to assume that the gimple parser already does the right > thing since it's supposed to already handle C expressions correctly. -gimple dumping doesn't elide dumping MEM_REFs to plain * so you see _1 = &__MEM <char[8]> (pa)[2]; _2 = __builtin_strlen (_1); I think the GIMPLE FE accepts *p as dereference in source, sth I should eventually fix (it likewise accepts ->). It then just does what the C frontend does since it shares most of its parsing. Richard. > Jeff
PR middle-end/90694 - incorrect representation of ADDR_EXPR involving a pointer to array gcc/ChangeLog: PR middle-end/90694 * tree-pretty-print.c (dump_generic_node): Add parentheses. gcc/testsuite/ChangeLog: PR middle-end/90694 * gcc.dg/tree-ssa/dump-5.c: New test. diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dump-5.c b/gcc/testsuite/gcc.dg/tree-ssa/dump-5.c new file mode 100644 index 00000000000..6807b5e9ef4 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/dump-5.c @@ -0,0 +1,15 @@ +/* PR middle-end/90694 - incorrect representation of ADDR_EXPR involving + a pointer to array + { dg-do compile } + { dg-options "-fdump-tree-original" } */ + +typedef char A8[8]; + +unsigned f (A8 *pa) +{ + return __builtin_strlen (&(*pa)[2]); +} + +/* Veriy the expression is correct in the dump: + { dg-final { scan-tree-dump-not "\\\&\\\*pa\\\[2\\\]" "original" } } + { dg-final { scan-tree-dump "\\\&\\\(\\\*pa\\\)\\\[2\\\]" "original" } } */ diff --git a/gcc/tree-pretty-print.c b/gcc/tree-pretty-print.c index 6645a646617..30d1d65e6bc 100644 --- a/gcc/tree-pretty-print.c +++ b/gcc/tree-pretty-print.c @@ -1676,9 +1676,17 @@ dump_generic_node (pretty_printer *pp, tree node, int spc, dump_flags_t flags, { if (TREE_CODE (TREE_OPERAND (node, 0)) != ADDR_EXPR) { + /* Enclose pointers to arrays in parentheses. */ + tree op0 = TREE_OPERAND (node, 0); + tree op0type = TREE_TYPE (op0); + if (POINTER_TYPE_P (op0type) + && TREE_CODE (TREE_TYPE (op0type)) == ARRAY_TYPE) + pp_left_paren (pp); pp_star (pp); - dump_generic_node (pp, TREE_OPERAND (node, 0), - spc, flags, false); + dump_generic_node (pp, op0, spc, flags, false); + if (POINTER_TYPE_P (op0type) + && TREE_CODE (TREE_TYPE (op0type)) == ARRAY_TYPE) + pp_right_paren (pp); } else dump_generic_node (pp,