This patch does two things: it fixes PR56466 by calling fix_loop_structure in case we're changing a loop, and secondly, it makes verifiyng loops in the unroller cheaper: there's no need to verify each loop, we can do it once after all transformations (verify_loop_structure is being called via fix_loop_structure).
Regtested/bootstrapped on x86_64-linux, ok for trunk? 2013-02-27 Marek Polacek <pola...@redhat.com> PR rtl-optimization/56466 * loop-unroll.c (unroll_and_peel_loops): Call fix_loop_structure if we're changing a loop. (peel_loops_completely): Likewise. * gcc.dg/pr56466.c: New test. --- gcc/loop-unroll.c.mp 2013-02-27 11:13:01.915430193 +0100 +++ gcc/loop-unroll.c 2013-02-27 14:57:09.873168342 +0100 @@ -207,7 +207,7 @@ void unroll_and_peel_loops (int flags) { struct loop *loop; - bool check; + bool changed = false; loop_iterator li; /* First perform complete loop peeling (it is almost surely a win, @@ -220,7 +220,6 @@ unroll_and_peel_loops (int flags) /* Scan the loops, inner ones first. */ FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) { - check = true; /* And perform the appropriate transformations. */ switch (loop->lpt_decision.decision) { @@ -229,30 +228,33 @@ unroll_and_peel_loops (int flags) gcc_unreachable (); case LPT_PEEL_SIMPLE: peel_loop_simple (loop); + changed |= true; break; case LPT_UNROLL_CONSTANT: unroll_loop_constant_iterations (loop); + changed |= true; break; case LPT_UNROLL_RUNTIME: unroll_loop_runtime_iterations (loop); + changed |= true; break; case LPT_UNROLL_STUPID: unroll_loop_stupid (loop); + changed |= true; break; case LPT_NONE: - check = false; break; default: gcc_unreachable (); } - if (check) - { -#ifdef ENABLE_CHECKING - verify_loop_structure (); -#endif - } } + if (changed) + { + calculate_dominance_info (CDI_DOMINATORS); + fix_loop_structure (NULL); + } + iv_analysis_done (); } @@ -283,6 +285,7 @@ peel_loops_completely (int flags) { struct loop *loop; loop_iterator li; + bool changed = false; /* Scan the loops, the inner ones first. */ FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) @@ -306,11 +309,15 @@ peel_loops_completely (int flags) { report_unroll_peel (loop, locus); peel_loop_completely (loop); -#ifdef ENABLE_CHECKING - verify_loop_structure (); -#endif + changed = true; } } + + if (changed) + { + calculate_dominance_info (CDI_DOMINATORS); + fix_loop_structure (NULL); + } } /* Decide whether unroll or peel loops (depending on FLAGS) and how much. */ --- gcc/testsuite/gcc.dg/pr56466.c.mp 2013-02-27 12:43:44.468886756 +0100 +++ gcc/testsuite/gcc.dg/pr56466.c 2013-02-27 12:46:36.385390735 +0100 @@ -0,0 +1,31 @@ +/* PR rtl-optimization/56466 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -w -funroll-loops" } */ + +int a, b, c; + +void +f (void) +{ + for (; b; b++) + { + if (0) + for (; b < 0; b++) + if (1 % 0) + { + while (1) + { + a = 0; + lbl1: + c++; + } + lbl2: + ; + } + + goto lbl1; + } + + a = 0; + goto lbl2; +} Marek