[PATCH] run early sprintf warning after SSA (PR 100325)

[Martin Sebor <msebor@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 498 bytes --]

With no optimization, -Wformat-overflow and -Wformat-truncation
runs early to detect a subset of simple bugs.  But as it turns out,
the pass runs just a tad too early, before SSA.  That causes it to
miss a class of problems that can easily be detected once code is
in SSA form, and I would expect might also cause false positives.

The attached change moves the sprintf pass just after pass_build_ssa,
similar to other early flow-sensitive warnings (-Wnonnull-compare and
-Wuninitialized).

Martin

[-- Attachment #2: gcc-100325.diff --]
[-- Type: text/x-patch, Size: 2091 bytes --]

PR middle-end/100325 - missing warning with -O0 on sprintf overflow with pointer plus offset

gcc/ChangeLog:

	* passes.def (pass_warn_printf): Run after SSA.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/builtin-sprintf-warn-26.c: New test.

diff --git a/gcc/passes.def b/gcc/passes.def
index 55e8164d56b..de39fa48b3d 100644
--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -45,7 +45,6 @@ along with GCC; see the file COPYING3.  If not see
   NEXT_PASS (pass_warn_function_return);
   NEXT_PASS (pass_coroutine_early_expand_ifns);
   NEXT_PASS (pass_expand_omp);
-  NEXT_PASS (pass_warn_printf);
   NEXT_PASS (pass_walloca, /*strict_mode_p=*/true);
   NEXT_PASS (pass_build_cgraph_edges);
   TERMINATE_PASS_LIST (all_lowering_passes)
@@ -58,6 +57,7 @@ along with GCC; see the file COPYING3.  If not see
   PUSH_INSERT_PASSES_WITHIN (pass_build_ssa_passes)
       NEXT_PASS (pass_fixup_cfg);
       NEXT_PASS (pass_build_ssa);
+      NEXT_PASS (pass_warn_printf);
       NEXT_PASS (pass_warn_nonnull_compare);
       NEXT_PASS (pass_early_warn_uninitialized);
       NEXT_PASS (pass_ubsan);
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-26.c b/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-26.c
index 16a551d9c8d..677b6345c5c 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-26.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/builtin-sprintf-warn-26.c
@@ -22,17 +22,17 @@ void nowarn_4m3 ()
 void warn_2m1 ()
 {
   char *p = a + 2;
-  sprintf (p - 1, "%i", 123);   // { dg-warning "-Wformat-overflow" "pr100325" { xfail *-*-* } }
+  sprintf (p - 1, "%i", 123);   // { dg-warning "-Wformat-overflow" "pr100325" }
 }
 
 void warn_3m1 ()
 {
   char *p = a + 3;
-  sprintf (p - 1, "%i", 12);    // { dg-warning "-Wformat-overflow" "pr100325" { xfail *-*-* } }
+  sprintf (p - 1, "%i", 12);    // { dg-warning "-Wformat-overflow" "pr100325" }
 }
 
 void warn_4m1 ()
 {
   char *p = a + 4;
-  sprintf (p - 1, "%i", 1);     // { dg-warning "-Wformat-overflow" "pr100325" { xfail *-*-* } }
+  sprintf (p - 1, "%i", 1);     // { dg-warning "-Wformat-overflow" "pr100325" }
 }