BZ83477 is another case where we had an VR_UNDEFINED range for source
operand during jump threading.
In this instance we had a PHI argument that was a constant. During
threading we record that the PHI result has the constant as its value.
I mistakenly thought that would avoid the need to mess around with the
value range unwinding stack. After all if the PHI result has a constant
value, we can just use the constant value.
But we handle generation of output ranges for a given statement before
we do const/copy propagation and simplification.
So we used the VR_UNDEFINED range for the condition in a COND_EXPR rhs
of a gimple assignment. This resulted in an incorrect output range for
the assignment that was later used in other jump threading decisions.
The fix is to always push a range for a non-virtual PHI during jump
threading. WHen the source operand is an SSA_NAME, we can just copy its
range. When the source operand is an INTEGER_CST, we can create a range
from that. Otherwise we use VR_VARYING.
I'd hoped this would fix the 435.gromacs problem, but it doesn't appear
to do so :(
Bootstrapped and regression tested on x86_64. Installing on the trunk.
Jeff
commit d69c59491a47db627c2429abef7547e7f005fc40
Author: Jeff Law <l...@torsion.usersys.redhat.com>
Date: Tue Dec 19 15:07:12 2017 -0500
PR tree-optimization/83477
* tree-ssa-threadedge.c (record_temporary_equivalences_from_phis):
For
a non-virtual PHI, always push a new range.
PR tree-optimization/83477
* gcc.c-torture/execute/pr83477.c: New test.
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4581f41d8fb..8a80f18045b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2017-12-18 Jeff Law <l...@redhat.com>
+
+ PR tree-optimization/83477
+ * tree-ssa-threadedge.c (record_temporary_equivalences_from_phis): For
+ a non-virtual PHI, always push a new range.
+
2017-12-19 Martin Sebor <mse...@redhat.com>
PR middle-end/77608
@@ -195,7 +201,6 @@
* tree-ssa-dom.c (record_equivalences_from_phis): Fix handling
of degenerates resulting from ignoring an edge.
->>>>>>> .r255835
2017-12-18 Martin Sebor <mse...@redhat.com>
PR middle-end/83373
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 63d671374e3..b32cb7a09fa 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-12-18 Jeff Law <l...@redhat.com>
+
+ PR tree-optimization/83477
+ * gcc.c-torture/execute/pr83477.c: New test.
+
2017-12-19 Martin Sebor <mse...@redhat.com>
PR middle-end/77608
@@ -63,7 +68,6 @@
PR ipa/83346
* g++.dg/ipa/pr82801.C: New test.
->>>>>>> .r255835
2017-12-18 Martin Sebor <mse...@redhat.com>
PR middle-end/83373
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr83477.c
b/gcc/testsuite/gcc.c-torture/execute/pr83477.c
new file mode 100644
index 00000000000..de667fd7d68
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr83477.c
@@ -0,0 +1,22 @@
+int yf = 0;
+
+void
+pl (int q5, int nd)
+{
+ unsigned int hp = q5;
+ int zx = (q5 == 0) ? hp : (hp / q5);
+
+ yf = ((nd < 2) * zx != 0) ? nd : 0;
+}
+
+int
+main (void)
+{
+ pl (1, !yf);
+ if (yf != 1)
+ __builtin_abort ();
+
+ return 0;
+}
+
+
diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c
index 1fafd7b5932..0c782f51697 100644
--- a/gcc/tree-ssa-threadedge.c
+++ b/gcc/tree-ssa-threadedge.c
@@ -156,11 +156,37 @@ record_temporary_equivalences_from_phis (edge e,
const_and_copies->record_const_or_copy (dst, src);
/* Also update the value range associated with DST, using
- the range from SRC. */
- if (evrp_range_analyzer && TREE_CODE (src) == SSA_NAME)
+ the range from SRC.
+
+ Note that even if SRC is a constant we need to set a suitable
+ output range so that VR_UNDEFINED ranges do not leak through. */
+ if (evrp_range_analyzer)
{
- value_range *vr = evrp_range_analyzer->get_value_range (src);
- evrp_range_analyzer->push_value_range (dst, vr);
+ /* Get an empty new VR we can pass to update_value_range and save
+ away in the VR stack. */
+ vr_values *vr_values = evrp_range_analyzer->get_vr_values ();
+ value_range *new_vr = vr_values->allocate_value_range ();
+ memset (new_vr, 0, sizeof (value_range));
+
+ /* There are three cases to consider:
+
+ First if SRC is an SSA_NAME, then we can copy the value
+ range from SRC into NEW_VR.
+
+ Second if SRC is an INTEGER_CST, then we can just wet
+ NEW_VR to a singleton range.
+
+ Otherwise set NEW_VR to varying. This may be overly
+ conservative. */
+ if (TREE_CODE (src) == SSA_NAME)
+ copy_value_range (new_vr, vr_values->get_value_range (src));
+ else if (TREE_CODE (src) == INTEGER_CST)
+ set_value_range_to_value (new_vr, src, NULL);
+ else
+ set_value_range_to_varying (new_vr);
+
+ /* This is a temporary range for DST, so push it. */
+ evrp_range_analyzer->push_value_range (dst, new_vr);
}
}
return true;
