In C++ code the clobber gets in the way of phiprop.
E.g.
```
if (lr_bitpos.2401_412 < rr_bitpos.2402_413)
goto <bb 198>; [INV]
else
goto <bb 197>; [INV]
<bb 197> :
<bb 198> :
MEM[(struct poly_int *)&D.192544] ={v} {CLOBBER(bob)};
_1060 = MEM[(const long int &)iftmp.2400_515];
```
The above comes from fold-const.cc. The clobber in the above case
is the clobber from the start of the constructor but other clobbers
can also get in the way, see gcc.dg/tree-ssa/phiprop-2.c for an example.
This shows up in a lot of C++ code where std::min/max (or even ?: like in the
fold-const.cc case) is used with in connection of constructors.
So optimizing this early in phiprop can improve code generation and compile
time speed.
g++.dg/tree-ssa/phiprop-2.C contains the reduced testcase from fold-const.cc.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/116823
gcc/ChangeLog:
* tree-ssa-phiprop.cc (phiprop_insert_phi): Get
the use_vuse before the looping of the phi arguments,
also skip over clobbers to get the use_vuse.
(propagate_with_phi): Skip over clobbers for the vuse.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/phiprop-2.c: New test.
* g++.dg/tree-ssa/phiprop-1.C: New test.
* g++.dg/tree-ssa/phiprop-2.C: New test.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
gcc/testsuite/g++.dg/tree-ssa/phiprop-1.C | 23 +++++++++++++++++++
gcc/testsuite/g++.dg/tree-ssa/phiprop-2.C | 25 +++++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/phiprop-2.c | 27 +++++++++++++++++++++++
gcc/tree-ssa-phiprop.cc | 25 ++++++++++++++++++++-
4 files changed, 99 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/tree-ssa/phiprop-1.C
create mode 100644 gcc/testsuite/g++.dg/tree-ssa/phiprop-2.C
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/phiprop-2.c
diff --git a/gcc/testsuite/g++.dg/tree-ssa/phiprop-1.C
b/gcc/testsuite/g++.dg/tree-ssa/phiprop-1.C
new file mode 100644
index 00000000000..e3388d1d157
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/phiprop-1.C
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-phiprop1-details -fdump-tree-release_ssa" } */
+
+/* PR tree-optimization/116823 */
+/* The clobber on a should not get in the way of phiprop here even if
+ this is undefined code. */
+/* We should have MIN_EXPR early on then too. */
+
+static inline
+const int &c(const int &d, const int &e) {
+ if (d < e)
+ return d;
+ return e;
+}
+
+int g(int i, struct f *ff)
+{
+ const int &a = c(i, 10);
+ return a;
+}
+/* { dg-final { scan-tree-dump-times "Inserting PHI for result of load" 1
"phiprop1"} } */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "release_ssa"} } */
+
diff --git a/gcc/testsuite/g++.dg/tree-ssa/phiprop-2.C
b/gcc/testsuite/g++.dg/tree-ssa/phiprop-2.C
new file mode 100644
index 00000000000..1a0d6ed92ee
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/phiprop-2.C
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-phiprop1-details -fdump-tree-release_ssa" } */
+
+/* PR tree-optimization/116823 */
+/* The clobber on the temp s2 should not get in the way of phiprop here. */
+/* We should have MAX_EXPR early on then too. */
+/* This is derived from fold-const.cc; s2 is similar to poly_int. */
+
+struct s2
+{
+ int i;
+ s2(const int &a) : i (a) {}
+};
+
+
+int h(s2 b);
+
+int g(int l, int r)
+{
+ return h(l > r ? l : r);
+}
+
+/* { dg-final { scan-tree-dump-times "Inserting PHI for result of load" 1
"phiprop1"} } */
+/* { dg-final { scan-tree-dump-times "MAX_EXPR" 1 "release_ssa"} } */
+
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phiprop-2.c
b/gcc/testsuite/gcc.dg/tree-ssa/phiprop-2.c
new file mode 100644
index 00000000000..546031e63d7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phiprop-2.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-phiprop1-details -fdump-tree-release_ssa" } */
+
+/* PR tree-optimization/116823 */
+/* The clobber on b should not get in the way of phiprop here. */
+/* We should have MIN_EXPR early on. */
+
+void f(int *);
+
+int g(int i)
+{
+ const int t = 10;
+ const int *a;
+ {
+ int b;
+ f(&b);
+ if (t < i)
+ a = &t;
+ else
+ a = &i;
+ }
+ return *a;
+}
+
+/* { dg-final { scan-tree-dump-times "Inserting PHI for result of load" 1
"phiprop1"} } */
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "release_ssa"} } */
+
diff --git a/gcc/tree-ssa-phiprop.cc b/gcc/tree-ssa-phiprop.cc
index 2a1cdae46d2..f04990e8cb4 100644
--- a/gcc/tree-ssa-phiprop.cc
+++ b/gcc/tree-ssa-phiprop.cc
@@ -159,6 +159,20 @@ phiprop_insert_phi (basic_block bb, gphi *phi, gimple
*use_stmt,
}
gphi *vphi = get_virtual_phi (bb);
+ tree use_vuse = gimple_vuse (use_stmt);
+ gimple *def_stmt = SSA_NAME_DEF_STMT (use_vuse);
+ /* Skip over clobbers in the same bb as the use
+ as they don't interfer with loads. */
+ while (!SSA_NAME_IS_DEFAULT_DEF (use_vuse)
+ && gimple_clobber_p (def_stmt)
+ && gimple_bb (def_stmt) == bb)
+ {
+ use_vuse = gimple_vuse (def_stmt);
+ def_stmt = SSA_NAME_DEF_STMT (use_vuse);
+ }
+ /* If there is a vphi, then the def statement of the
+ vuse has to be a phi. */
+ gcc_assert (!vphi || is_a<gphi *>(def_stmt));
/* Add PHI arguments for each edge inserting loads of the
addressable operands. */
@@ -204,7 +218,7 @@ phiprop_insert_phi (basic_block bb, gphi *phi, gimple
*use_stmt,
if (vphi)
vuse = PHI_ARG_DEF_FROM_EDGE (vphi, e);
else
- vuse = gimple_vuse (use_stmt);
+ vuse = use_vuse;
}
else
/* For the aggregate copy case updating virtual operands
@@ -377,6 +391,15 @@ propagate_with_phi (basic_block bb, gphi *phi, struct
phiprop_d *phivn,
def is an edge-inserted one we know it dominates us. */
vuse = gimple_vuse (use_stmt);
def_stmt = SSA_NAME_DEF_STMT (vuse);
+ /* Skip over clobbers in the same bb as the use
+ as they don't interfer with loads. */
+ while (!SSA_NAME_IS_DEFAULT_DEF (vuse)
+ && gimple_clobber_p (def_stmt)
+ && gimple_bb (def_stmt) == bb)
+ {
+ vuse = gimple_vuse (def_stmt);
+ def_stmt = SSA_NAME_DEF_STMT (vuse);
+ }
if (!SSA_NAME_IS_DEFAULT_DEF (vuse)
&& (gimple_bb (def_stmt) == bb
|| (gimple_bb (def_stmt)
--
2.43.0
