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Further refinement to -Wswitch-unreachable
- From: Marek Polacek <polacek at redhat dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, Jason Merrill <jason at redhat dot com>, Joseph Myers <joseph at codesourcery dot com>
- Cc: Martin Sebor <msebor at redhat dot com>
- Date: Thu, 26 May 2016 20:44:13 +0200
- Subject: Further refinement to -Wswitch-unreachable
- Authentication-results: sourceware.org; auth=none
Martin complained that -Wswitch-unreachable wouldn't warn on try-blocks,
either compiler-generated or user-written. This patch, which looks into
GIMPLE_TRY's body, seems to DTRT for both.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2016-05-26 Marek Polacek <polacek@redhat.com>
* gimplify.c (gimplify_switch_expr): Also handle GIMPLE_TRY.
* c-c++-common/Wswitch-unreachable-3.c: New test.
* g++.dg/warn/Wswitch-unreachable-1.C: New test.
diff --git gcc/gimplify.c gcc/gimplify.c
index 8316bb8..8b7dddc 100644
--- gcc/gimplify.c
+++ gcc/gimplify.c
@@ -1609,10 +1609,17 @@ gimplify_switch_expr (tree *expr_p, gimple_seq *pre_p)
while (gimple_code (seq) == GIMPLE_BIND)
seq = gimple_bind_body (as_a <gbind *> (seq));
gimple *stmt = gimple_seq_first_stmt (seq);
- enum gimple_code code = gimple_code (stmt);
- if (code != GIMPLE_LABEL && code != GIMPLE_TRY)
+ if (gimple_code (stmt) == GIMPLE_TRY)
{
- if (code == GIMPLE_GOTO
+ /* A compiler-generated cleanup or a user-written try block.
+ Try to get the first statement in its try-block, for better
+ location. */
+ if ((seq = gimple_try_eval (stmt)))
+ stmt = gimple_seq_first_stmt (seq);
+ }
+ if (gimple_code (stmt) != GIMPLE_LABEL)
+ {
+ if (gimple_code (stmt) == GIMPLE_GOTO
&& TREE_CODE (gimple_goto_dest (stmt)) == LABEL_DECL
&& DECL_ARTIFICIAL (gimple_goto_dest (stmt)))
/* Don't warn for compiler-generated gotos. These occur
diff --git gcc/testsuite/c-c++-common/Wswitch-unreachable-3.c gcc/testsuite/c-c++-common/Wswitch-unreachable-3.c
index e69de29..3748701 100644
--- gcc/testsuite/c-c++-common/Wswitch-unreachable-3.c
+++ gcc/testsuite/c-c++-common/Wswitch-unreachable-3.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+extern void f (int *, int);
+
+void
+g (int i)
+{
+ switch (i)
+ {
+ int a[3];
+ __builtin_memset (a, 0, sizeof a); /* { dg-warning "statement will never be executed" } */
+
+ default:
+ f (a, 3);
+ }
+}
diff --git gcc/testsuite/g++.dg/warn/Wswitch-unreachable-1.C gcc/testsuite/g++.dg/warn/Wswitch-unreachable-1.C
index e69de29..99d9a83 100644
--- gcc/testsuite/g++.dg/warn/Wswitch-unreachable-1.C
+++ gcc/testsuite/g++.dg/warn/Wswitch-unreachable-1.C
@@ -0,0 +1,34 @@
+// { dg-do compile }
+
+extern int j;
+
+void
+f (int i)
+{
+ switch (i) // { dg-warning "statement will never be executed" }
+ {
+ try
+ {
+ }
+ catch (...)
+ {
+ }
+ case 1:;
+ }
+}
+
+void
+g (int i)
+{
+ switch (i)
+ {
+ try
+ {
+ j = 42; // { dg-warning "statement will never be executed" }
+ }
+ catch (...)
+ {
+ }
+ case 1:;
+ }
+}
Marek