From 5b32d4548a28e4783a5a965dee1241f41f27a952 Mon Sep 17 00:00:00 2001 From: mpolacek Date: Mon, 13 Jun 2016 08:57:02 +0000 Subject: [PATCH] PR middle-end/71476 * gimplify.c (maybe_warn_switch_unreachable): Factored out of gimplify_switch_expr. (warn_switch_unreachable_r): New function. * c-c++-common/Wswitch-unreachable-4.c: New test. * gcc.dg/Wswitch-unreachable-2.c: New test. * g++.dg/tm/jump1.C: Move dg-warning. upstream hash: 1a54d3bee5c40687c53b2680d0b110f23a193713 git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@237367 138bc75d-0d04-0410-961f-82ee72b054a4 Change-Id: Ie8bc6fb965fdb08c7e76ee02fe01eec4707336b0 --- gcc/gimplify.c | 102 ++++++++++++++------- gcc/testsuite/c-c++-common/Wswitch-unreachable-4.c | 25 +++++ gcc/testsuite/g++.dg/tm/jump1.C | 4 +- gcc/testsuite/gcc.dg/Wswitch-unreachable-2.c | 12 +++ 4 files changed, 108 insertions(+), 35 deletions(-) create mode 100644 gcc/testsuite/c-c++-common/Wswitch-unreachable-4.c create mode 100644 gcc/testsuite/gcc.dg/Wswitch-unreachable-2.c diff --git a/gcc/gimplify.c b/gcc/gimplify.c index 056d5ef..a66b846 100644 --- a/gcc/gimplify.c +++ b/gcc/gimplify.c @@ -1552,6 +1552,73 @@ gimplify_statement_list (tree *expr_p, gimple_seq *pre_p) return GS_ALL_DONE; } +/* Callback for walk_gimple_seq. */ + +static tree +warn_switch_unreachable_r (gimple_stmt_iterator *gsi_p, bool *handled_ops_p, + struct walk_stmt_info *wi) +{ + gimple *stmt = gsi_stmt (*gsi_p); + + *handled_ops_p = true; + switch (gimple_code (stmt)) + { + case GIMPLE_TRY: + /* A compiler-generated cleanup or a user-written try block. + If it's empty, don't dive into it--that would result in + worse location info. */ + if (gimple_try_eval (stmt) == NULL) + { + wi->info = stmt; + return integer_zero_node; + } + /* Fall through. */ + case GIMPLE_BIND: + case GIMPLE_CATCH: + case GIMPLE_EH_FILTER: + case GIMPLE_TRANSACTION: + /* Walk the sub-statements. */ + *handled_ops_p = false; + break; + default: + /* Save the first "real" statement (not a decl/lexical scope/...). */ + wi->info = stmt; + return integer_zero_node; + } + return NULL_TREE; +} + +/* Possibly warn about unreachable statements between switch's controlling + expression and the first case. SEQ is the body of a switch expression. */ + +static void +maybe_warn_switch_unreachable (gimple_seq seq) +{ + if (!warn_switch_unreachable + /* This warning doesn't play well with Fortran when optimizations + are on. */ + || lang_GNU_Fortran () + || seq == NULL) + return; + + struct walk_stmt_info wi; + memset (&wi, 0, sizeof (wi)); + walk_gimple_seq (seq, warn_switch_unreachable_r, NULL, &wi); + gimple *stmt = (gimple *) wi.info; + + if (stmt && 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 + in Duff's devices, for example. */; + else + warning_at (gimple_location (stmt), OPT_Wswitch_unreachable, + "statement will never be executed"); + } +} + /* Gimplify a SWITCH_EXPR, and collect the vector of labels it can branch to. */ @@ -1589,39 +1656,8 @@ gimplify_switch_expr (tree *expr_p, gimple_seq *pre_p) gimplify_stmt (&SWITCH_BODY (switch_expr), &switch_body_seq); - /* Possibly warn about unreachable statements between switch's - controlling expression and the first case. */ - if (warn_switch_unreachable - /* This warning doesn't play well with Fortran when optimizations - are on. */ - && !lang_GNU_Fortran () - && switch_body_seq != NULL) - { - gimple_seq seq = switch_body_seq; - /* Look into the innermost lexical scope. */ - while (gimple_code (seq) == GIMPLE_BIND) - seq = gimple_bind_body (as_a (seq)); - gimple *stmt = gimple_seq_first_stmt (seq); - if (gimple_code (stmt) == GIMPLE_TRY) - { - /* 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 - in Duff's devices, for example. */; - else - warning_at (gimple_location (stmt), OPT_Wswitch_unreachable, - "statement will never be executed"); - } - } + maybe_warn_switch_unreachable (switch_body_seq); + labels = gimplify_ctxp->case_labels; gimplify_ctxp->case_labels = saved_labels; diff --git a/gcc/testsuite/c-c++-common/Wswitch-unreachable-4.c b/gcc/testsuite/c-c++-common/Wswitch-unreachable-4.c new file mode 100644 index 0000000..e7378a7 --- /dev/null +++ b/gcc/testsuite/c-c++-common/Wswitch-unreachable-4.c @@ -0,0 +1,25 @@ +/* { dg-do compile } */ + +void +foo (int a, int b) +{ + switch (a) + { + { int c; } + { int d; } + { int e; } + b++; /* { dg-warning "statement will never be executed" } */ + case 1: + break; + } + + switch (a) + { + { int c; } + { int d = 1; } /* { dg-warning "statement will never be executed" } */ + { int e; } + b++; + case 1: + break; + } +} diff --git a/gcc/testsuite/g++.dg/tm/jump1.C b/gcc/testsuite/g++.dg/tm/jump1.C index e28282d..a27c201 100644 --- a/gcc/testsuite/g++.dg/tm/jump1.C +++ b/gcc/testsuite/g++.dg/tm/jump1.C @@ -14,8 +14,8 @@ void f() switch (i) { - synchronized { // { dg-warning "statement will never be executed" } - ++i; + synchronized { + ++i; // { dg-warning "statement will never be executed" } case 42: // { dg-error "" } ++i; } diff --git a/gcc/testsuite/gcc.dg/Wswitch-unreachable-2.c b/gcc/testsuite/gcc.dg/Wswitch-unreachable-2.c new file mode 100644 index 0000000..343baea --- /dev/null +++ b/gcc/testsuite/gcc.dg/Wswitch-unreachable-2.c @@ -0,0 +1,12 @@ +/* PR middle-end/71476 */ +/* { dg-do compile } */ +/* { dg-options "-Wswitch-unreachable" } */ + +void +foo (int a) +{ + switch (a) + { + void f (void) { } + } +} -- 2.7.4