https://gcc.gnu.org/g:942a25fa89d7b0ea3e6e36bec4e5e93b3a0e82d4
commit 942a25fa89d7b0ea3e6e36bec4e5e93b3a0e82d4
Author: Alexandre Oliva <ol...@adacore.com>
Date: Thu Dec 19 00:19:34 2024 -0300
add options to control ifcombine
Introduce flags to disable ifcombine as a whole, or its new components.
Disable the potentially quadratic noncontiguous ifcombine at -O1.
Adjust the tests that expected it with -O to use -O2 instead.
for gcc/ChangeLog
* common.opt (fcombine-conditionals): New.
(fcombine-field-conditionals): New.
(fcombine-noncontiguous-conditionals): New.
* doc/invoke.texi: Document them.
* tree-ssa-ifcombine.cc (ifcombine_ifandif): Don't call
fold_truth_andor if -fno-combine-field-conditionals.
(tree_ssa_ifcombine_bb): Quit after the first attempt under
-fno-combine-noncontiguous-conditionals.
(pass_tree_ifcombine::gate): New.
for gcc/testsuite/ChangeLog
* gcc.dg/field-merge-1.c: Bump to -O2.
* gcc.dg/field-merge-2.c: Likewise.
* gcc.dg/field-merge-3.c: Likewise.
* gcc.dg/field-merge-4.c: Likewise.
* gcc.dg/field-merge-5.c: Likewise.
* gcc.dg/field-merge-6.c: Likewise.
* gcc.dg/field-merge-7.c: Likewise.
* gcc.dg/field-merge-8.c: Likewise.
* gcc.dg/field-merge-9.c: Likewise.
* gcc.dg/field-merge-10.c: Likewise.
* gcc.dg/field-merge-11.c: Likewise.
* gcc.dg/field-merge-13.c: Likewise.
* gcc.dg/field-merge-14.c: Likewise.
* gcc.dg/field-merge-15.c: Likewise.
* gcc.dg/field-merge-16.c: Likewise.
Diff:
---
gcc/common.opt | 12 ++++++++++++
gcc/doc/invoke.texi | 30 ++++++++++++++++++++++++++++
gcc/testsuite/gcc.dg/field-merge-1.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-10.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-11.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-13.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-14.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-15.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-16.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-2.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-3.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-4.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-5.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-6.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-7.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-8.c | 2 +-
gcc/testsuite/gcc.dg/field-merge-9.c | 2 +-
gcc/tree-ssa-ifcombine.cc | 37 +++++++++++++++++++++++------------
18 files changed, 82 insertions(+), 27 deletions(-)
diff --git a/gcc/common.opt b/gcc/common.opt
index 1b72826d44b1..aa5ad7974112 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1241,6 +1241,18 @@ fcode-hoisting
Common Var(flag_code_hoisting) Optimization
Enable code hoisting.
+fcombine-conditionals
+Common Var(flag_tree_ifcombine) Init(-1) Optimization
+Combine conditionals, with the ifcombine optimization pass.
+
+fcombine-field-conditionals
+Common Var(flag_tree_ifcombine_fieldmerge) Init(-1) Optimization
+Combine conditionals involving separate fields
+
+fcombine-noncontiguous-conditionals
+Common Var(flag_tree_ifcombine_noncontig) Init(-1) Optimization
+Combine conditionals from noncontiguous blocks
+
fcombine-stack-adjustments
Common Var(flag_combine_stack_adjustments) Optimization
Looks for opportunities to reduce stack adjustments and stack references.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 8ed5536365f7..317b1dd233a6 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -570,6 +570,8 @@ Objective-C and Objective-C++ Dialects}.
-fassociative-math -fauto-profile -fauto-profile[=@var{path}]
-fauto-inc-dec -fbranch-probabilities
-fcaller-saves
+-fcombine-conditionals -fcombine-field-conditionals
+-fcombine-noncontiguous-conditionals
-fcombine-stack-adjustments -fconserve-stack
-ffold-mem-offsets
-fcompare-elim -fcprop-registers -fcrossjumping
@@ -12633,6 +12635,8 @@ complexity than at @option{-O}.
@c Please keep the following list alphabetized.
@gccoptlist{-fauto-inc-dec
-fbranch-count-reg
+-fcombine-conditionals
+-fcombine-field-conditionals
-fcombine-stack-adjustments
-fcompare-elim
-fcprop-registers
@@ -12693,6 +12697,7 @@ also turns on the following optimization flags:
@gccoptlist{-falign-functions -falign-jumps
-falign-labels -falign-loops
-fcaller-saves
+-fcombine-noncontiguous-conditionals
-fcode-hoisting
-fcrossjumping
-fcse-follow-jumps -fcse-skip-blocks
@@ -13676,6 +13681,31 @@ those which have no call-preserved registers to use
instead.
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@opindex fcombine-conditionals
+@opindex fno-combine-conditionals
+@item -fcombine-conditionals
+Enable combination of conditionals from blocks without side effects.
+
+It has no effect when not optimizing.
+
+@opindex fcombine-field-conditionals
+@opindex fno-combine-field-conditionals
+@item -fcombine-field-conditionals
+Enable combination of conditionals involving different fields, and
+similar transformations that widen loads to save compares.
+
+It has no effect if @option{-fcombine-conditionals} is not enabled.
+
+@opindex fcombine-noncontiguous-conditionals
+@opindex fno-combine-noncontiguous-conditionals
+@item -fcombine-noncontiguous-conditionals
+Enable combination of conditionals that belong to the same chain of
+tests, even if they aren't adjacent.
+
+It has no effect if @option{-fcombine-conditionals} is not enabled.
+
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
@opindex fcombine-stack-adjustments
@item -fcombine-stack-adjustments
Tracks stack adjustments (pushes and pops) and stack memory references
diff --git a/gcc/testsuite/gcc.dg/field-merge-1.c
b/gcc/testsuite/gcc.dg/field-merge-1.c
index 1818e104437e..64905ca04d19 100644
--- a/gcc/testsuite/gcc.dg/field-merge-1.c
+++ b/gcc/testsuite/gcc.dg/field-merge-1.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O -save-temps -fdump-tree-optimized" } */
+/* { dg-options "-O2 -save-temps -fdump-tree-optimized" } */
/* Check that field loads compared with constants are merged, even if
tested out of order, and when fields straddle across alignment
diff --git a/gcc/testsuite/gcc.dg/field-merge-10.c
b/gcc/testsuite/gcc.dg/field-merge-10.c
index dca6febb7585..5ad33b906850 100644
--- a/gcc/testsuite/gcc.dg/field-merge-10.c
+++ b/gcc/testsuite/gcc.dg/field-merge-10.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
/* Check that we don't move loads across stores. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-11.c
b/gcc/testsuite/gcc.dg/field-merge-11.c
index fe627cddd7fd..66af1f0b21b0 100644
--- a/gcc/testsuite/gcc.dg/field-merge-11.c
+++ b/gcc/testsuite/gcc.dg/field-merge-11.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
/* Check that narrowing casts aren't ignored, and that same-field tests at
different widths aren't misoptimized. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-13.c
b/gcc/testsuite/gcc.dg/field-merge-13.c
index 7e4f4c499347..dc5259b1be8b 100644
--- a/gcc/testsuite/gcc.dg/field-merge-13.c
+++ b/gcc/testsuite/gcc.dg/field-merge-13.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O -fdump-tree-ifcombine-details" } */
+/* { dg-options "-O2 -fdump-tree-ifcombine-details" } */
/* Check that we optimize swapped compares, and that we don't load from objects
before they're fully initialized. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-14.c
b/gcc/testsuite/gcc.dg/field-merge-14.c
index 91d84cfebf19..0ef0942c176d 100644
--- a/gcc/testsuite/gcc.dg/field-merge-14.c
+++ b/gcc/testsuite/gcc.dg/field-merge-14.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O -fdump-tree-ifcombine-details" } */
+/* { dg-options "-O2 -fdump-tree-ifcombine-details" } */
/* Check that we don't get confused by multiple conversions. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-15.c
b/gcc/testsuite/gcc.dg/field-merge-15.c
index 34641e893c92..e365f8f86c2d 100644
--- a/gcc/testsuite/gcc.dg/field-merge-15.c
+++ b/gcc/testsuite/gcc.dg/field-merge-15.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O -fdump-tree-ifcombine-details" } */
+/* { dg-options "-O2 -fdump-tree-ifcombine-details" } */
/* Check that bitfield compares-with-zero turned into GT and LE compares with
powers-of-two minus 1 are optimized. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-16.c
b/gcc/testsuite/gcc.dg/field-merge-16.c
index 2ca23ea663a4..75783547eef6 100644
--- a/gcc/testsuite/gcc.dg/field-merge-16.c
+++ b/gcc/testsuite/gcc.dg/field-merge-16.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O -fdump-tree-ifcombine-details" } */
+/* { dg-options "-O2 -fdump-tree-ifcombine-details" } */
/* Check that tests for sign-extension bits are handled correctly. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-2.c
b/gcc/testsuite/gcc.dg/field-merge-2.c
index 80c573b31ddc..976d41e357ad 100644
--- a/gcc/testsuite/gcc.dg/field-merge-2.c
+++ b/gcc/testsuite/gcc.dg/field-merge-2.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
struct TL {
unsigned short a;
diff --git a/gcc/testsuite/gcc.dg/field-merge-3.c
b/gcc/testsuite/gcc.dg/field-merge-3.c
index f26e8a96ea04..6ea01007422f 100644
--- a/gcc/testsuite/gcc.dg/field-merge-3.c
+++ b/gcc/testsuite/gcc.dg/field-merge-3.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
const int BIG_ENDIAN_P = (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__);
diff --git a/gcc/testsuite/gcc.dg/field-merge-4.c
b/gcc/testsuite/gcc.dg/field-merge-4.c
index c629069e52b2..691f95fe94c8 100644
--- a/gcc/testsuite/gcc.dg/field-merge-4.c
+++ b/gcc/testsuite/gcc.dg/field-merge-4.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
struct T1 {
unsigned int zn;
diff --git a/gcc/testsuite/gcc.dg/field-merge-5.c
b/gcc/testsuite/gcc.dg/field-merge-5.c
index 1580b14bcc93..6fbab1760f0c 100644
--- a/gcc/testsuite/gcc.dg/field-merge-5.c
+++ b/gcc/testsuite/gcc.dg/field-merge-5.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
struct T1 {
unsigned int zn;
diff --git a/gcc/testsuite/gcc.dg/field-merge-6.c
b/gcc/testsuite/gcc.dg/field-merge-6.c
index 7fd48a138d14..49465682c1fa 100644
--- a/gcc/testsuite/gcc.dg/field-merge-6.c
+++ b/gcc/testsuite/gcc.dg/field-merge-6.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
/* { dg-shouldfail } */
/* Check that the third compare won't be pulled ahead of the second one and
diff --git a/gcc/testsuite/gcc.dg/field-merge-7.c
b/gcc/testsuite/gcc.dg/field-merge-7.c
index 728a29b6fafa..a6a2f0a3bb0e 100644
--- a/gcc/testsuite/gcc.dg/field-merge-7.c
+++ b/gcc/testsuite/gcc.dg/field-merge-7.c
@@ -1,5 +1,5 @@
/* { dg-do compile } */
-/* { dg-options "-O -fdump-tree-ifcombine-details" } */
+/* { dg-options "-O2 -fdump-tree-ifcombine-details" } */
/* Check that the third compare won't be combined with the first one. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-8.c
b/gcc/testsuite/gcc.dg/field-merge-8.c
index ae270e10070e..8d71f919b897 100644
--- a/gcc/testsuite/gcc.dg/field-merge-8.c
+++ b/gcc/testsuite/gcc.dg/field-merge-8.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O" } */
+/* { dg-options "-O2" } */
/* Check that conversions are not thrown away. */
diff --git a/gcc/testsuite/gcc.dg/field-merge-9.c
b/gcc/testsuite/gcc.dg/field-merge-9.c
index 04df54c2b74e..64fdfe3d0c6e 100644
--- a/gcc/testsuite/gcc.dg/field-merge-9.c
+++ b/gcc/testsuite/gcc.dg/field-merge-9.c
@@ -1,5 +1,5 @@
/* { dg-do run } */
-/* { dg-options "-O -fdump-tree-ifcombine-details" } */
+/* { dg-options "-O2 -fdump-tree-ifcombine-details" } */
/* Check that conversions and selections of similar bit ranges across different
types don't prevent combination. */
diff --git a/gcc/tree-ssa-ifcombine.cc b/gcc/tree-ssa-ifcombine.cc
index c9399a106945..108fa5b17dac 100644
--- a/gcc/tree-ssa-ifcombine.cc
+++ b/gcc/tree-ssa-ifcombine.cc
@@ -972,18 +972,19 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool
inner_inv,
gimple_cond_lhs (outer_cond),
gimple_cond_rhs (outer_cond),
gimple_bb (outer_cond)))
- && !(t = (fold_truth_andor_for_ifcombine
- (TRUTH_ANDIF_EXPR, boolean_type_node,
- gimple_location (outer_cond),
- outer_cond_code,
- gimple_cond_lhs (outer_cond),
- gimple_cond_rhs (outer_cond),
- gimple_location (inner_cond),
- inner_cond_code,
- gimple_cond_lhs (inner_cond),
- gimple_cond_rhs (inner_cond),
- single_pred (inner_cond_bb) != outer_cond_bb
- ? &ts : 0))))
+ && !(flag_tree_ifcombine_fieldmerge
+ && (t = (fold_truth_andor_for_ifcombine
+ (TRUTH_ANDIF_EXPR, boolean_type_node,
+ gimple_location (outer_cond),
+ outer_cond_code,
+ gimple_cond_lhs (outer_cond),
+ gimple_cond_rhs (outer_cond),
+ gimple_location (inner_cond),
+ inner_cond_code,
+ gimple_cond_lhs (inner_cond),
+ gimple_cond_rhs (inner_cond),
+ single_pred (inner_cond_bb) != outer_cond_bb
+ ? &ts : 0)))))
{
/* Only combine conditions in this fallback case if the blocks are
neighbors. */
@@ -1255,6 +1256,9 @@ tree_ssa_ifcombine_bb (basic_block inner_cond_bb)
/* Record the exit path taken by the outer condition. */
if (!exit_bb)
{
+ if (!flag_tree_ifcombine_noncontig)
+ break;
+
/* If we have removed the outer condition entirely, we need not
commit to an exit block yet, it's as if we'd merged the blocks and
were starting afresh. This is sound as long as we never replace
@@ -1369,6 +1373,15 @@ public:
{}
/* opt_pass methods: */
+ bool gate (function *) final override {
+ if (!flag_tree_ifcombine)
+ return false;
+
+ if (flag_tree_ifcombine_noncontig == -1)
+ flag_tree_ifcombine_noncontig = (optimize >= 2 || optimize_size);
+
+ return flag_tree_ifcombine;
+ }
unsigned int execute (function *) final override;
}; // class pass_tree_ifcombine
