operator_cast::op1_range() does some masking and calculations when a
higher precision value is cast to a lower precision one.
ie, it fills in the ranges for the upper bits and trys to produce more
usable results for the wind-back process. Part of that calculation
involved using PLUS_EXPR to the current range... for which
POINTER_TYPE_P does not have any support (It uses POINTER_PLUS which has
difference semantics)./ Thus the trap.
in this particular case
CopyFromUswc_src.2_1 = CopyFromUswc_src;
CopyFromUswc_src.3_2 = (long int) CopyFromUswc_src.2_1;
unaligned_12 = (unsigned int) CopyFromUswc_src.3_2;
if (unaligned_12 != 0)
goto <bb 4>; [INV]
else
goto <bb 5>; [INV]
3->4 (T) CopyFromUswc_src.2_1 : char * [1B, +INF]
3->4 (T) CopyFromUswc_src.3_2 : long int [-INF,
-4294967297][-4294967295, -1][1, +INF]
3->4 (T) unaligned_12 : unsigned int [1, +INF]
3->5 (F) CopyFromUswc_src.3_2 : long int [-INF, -4294967296][0,
0][4294967296, +INF]
3->5 (F) unaligned_12 : unsigned int [0, 0]
THis is what we produce now.
before this patch, we were not doing anything different for pointers, so
when processing:
CopyFromUswc_src.2_1 = CopyFromUswc_src;
we were calculating the RHS as a char * from
long int [-INF, -4294967297][-4294967295, -1][1, +INF]
which is a lot of work for very little, since we really only care about
zero, non-zero, and varying. We do occasionally track a constant
value.... and I'm leaving in that capability since it allows us to treat
0/NULL as just another constant, but thats all we really need.
Bootstrapped on x86_64-pc-linux-gnu, no regressions. Pushed.
commit c25b504636fec7bf8f181a84af83a52757ba7e89
Author: Andrew MacLeod <amacl...@redhat.com>
Date: Thu Dec 17 09:24:11 2020 -0500
Fix trap in pointer conversion in op1_range.
Processing op1_range for conversion between a non-pointer and pointer
shouldnt do any fancy math.
gcc/
PR tree-optimization/97750
* range-op.cc (operator_cast::op1_range): Handle pointers better.
gcc/testsuite/
* gcc.dg/pr97750.c: New.
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 36f9fd66cb3..a473f33169d 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -1850,6 +1850,31 @@ operator_cast::op1_range (irange &r, tree type,
tree lhs_type = lhs.type ();
gcc_checking_assert (types_compatible_p (op2.type(), type));
+ // If we are calculating a pointer, shortcut to what we really care about.
+ if (POINTER_TYPE_P (type))
+ {
+ // Conversion from other pointers or a constant (including 0/NULL)
+ // are straightforward.
+ if (POINTER_TYPE_P (lhs.type ())
+ || (lhs.singleton_p ()
+ && TYPE_PRECISION (lhs.type ()) >= TYPE_PRECISION (type)))
+ {
+ r = lhs;
+ range_cast (r, type);
+ }
+ else
+ {
+ // If the LHS is not a pointer nor a singleton, then it is
+ // either VARYING or non-zero.
+ if (!lhs.contains_p (build_zero_cst (lhs.type ())))
+ r.set_nonzero (type);
+ else
+ r.set_varying (type);
+ }
+ r.intersect (op2);
+ return true;
+ }
+
if (truncating_cast_p (op2, lhs))
{
if (lhs.varying_p ())
diff --git a/gcc/testsuite/gcc.dg/pr97750.c b/gcc/testsuite/gcc.dg/pr97750.c
new file mode 100644
index 00000000000..822b53abcff
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr97750.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/97750 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wall -Wextra" } */
+
+char CopyPlane_src;
+long CopyPlane_copy_pitch;
+char *CopyFromUswc_src;
+int CopyFromUswc_height;
+void CopyPlane(char *dst) {
+ __builtin_memcpy(dst, &CopyPlane_src, CopyPlane_copy_pitch);
+}
+void CopyFromUswc(long src_pitch) {
+ char *dst;
+ for (; CopyFromUswc_height;) {
+ unsigned unaligned = (long)CopyFromUswc_src;
+ if (unaligned)
+ CopyPlane(&dst[unaligned]); /* { dg-warning "may be used uninitialized" } */
+ CopyFromUswc_src += src_pitch;
+ }
+}
+