Last year I mentioned that -fthread-jumps was being ignored by the majority of our jump threading passes, and Jeff said he'd be in favor of fixing this.
This patch remedies the situation, but it does change existing behavior. Currently -fthread-jumps is only enabled for -O2, -O3, and -Os. This means that even if we restricted all jump threading passes with -fthread-jumps, DOM jump threading would still seep through since it runs at -O1. I propose this patch, but it does mean that DOM jump threading would have to be explicitly enabled with -O1 -fthread-jumps. An alternative would be to also offer a specific -fno-dom-threading, but that seems icky. OK pending tests? gcc/ChangeLog: * tree-ssa-threadbackward.c (pass_thread_jumps::gate): Check flag_thread_jumps. (pass_early_thread_jumps::gate): Same. * tree-ssa-threadedge.c (jump_threader::thread_outgoing_edges): Return if !flag_thread_jumps. * tree-ssa-threadupdate.c (jt_path_registry::register_jump_thread): Assert that flag_thread_jumps is true. --- gcc/testsuite/gcc.dg/tree-ssa/pr18133-2.c | 2 +- gcc/testsuite/gcc.dg/tree-ssa/pr18134.c | 2 +- gcc/tree-ssa-threadbackward.c | 4 ++-- gcc/tree-ssa-threadedge.c | 3 +++ gcc/tree-ssa-threadupdate.c | 2 ++ 5 files changed, 9 insertions(+), 4 deletions(-) diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr18133-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr18133-2.c index 8717640e327..1b409852189 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/pr18133-2.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr18133-2.c @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O1 -fdump-tree-optimized-blocks" } */ +/* { dg-options "-O1 -fthread-jumps -fdump-tree-optimized-blocks" } */ int c, d; diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr18134.c b/gcc/testsuite/gcc.dg/tree-ssa/pr18134.c index cd40ab2c162..d7f5d241eb9 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/pr18134.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr18134.c @@ -1,5 +1,5 @@ /* { dg-do compile } */ -/* { dg-options "-O1 -fdump-tree-optimized" } */ +/* { dg-options "-O1 -fthread-jumps -fdump-tree-optimized" } */ int foo (int a) { diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c index 95542079faf..8940728cbf2 100644 --- a/gcc/tree-ssa-threadbackward.c +++ b/gcc/tree-ssa-threadbackward.c @@ -943,7 +943,7 @@ public: bool pass_thread_jumps::gate (function *fun ATTRIBUTE_UNUSED) { - return flag_expensive_optimizations; + return flag_thread_jumps && flag_expensive_optimizations; } // Try to thread blocks in FUN. Return TRUE if any jump thread paths were @@ -1013,7 +1013,7 @@ public: bool pass_early_thread_jumps::gate (function *fun ATTRIBUTE_UNUSED) { - return true; + return flag_thread_jumps; } unsigned int diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c index ae77e5eb396..e6f0ff0b54b 100644 --- a/gcc/tree-ssa-threadedge.c +++ b/gcc/tree-ssa-threadedge.c @@ -1195,6 +1195,9 @@ jump_threader::thread_outgoing_edges (basic_block bb) int flags = (EDGE_IGNORE | EDGE_COMPLEX | EDGE_ABNORMAL); gimple *last; + if (!flag_thread_jumps) + return; + /* If we have an outgoing edge to a block with multiple incoming and outgoing edges, then we may be able to thread the edge, i.e., we may be able to statically determine which of the outgoing edges diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c index 2b9b8f81274..cf96c903668 100644 --- a/gcc/tree-ssa-threadupdate.c +++ b/gcc/tree-ssa-threadupdate.c @@ -2822,6 +2822,8 @@ jt_path_registry::cancel_invalid_paths (vec<jump_thread_edge *> &path) bool jt_path_registry::register_jump_thread (vec<jump_thread_edge *> *path) { + gcc_checking_assert (flag_thread_jumps); + if (!dbg_cnt (registered_jump_thread)) { path->release (); -- 2.31.1