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* [gcc(refs/vendors/redhat/heads/gcc-10-branch)] varasm: Fix output_constructor where a RANGE_EXPR index needs to skip some elts [PR94303]
@ 2020-03-25 10:13 Jakub Jelinek
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From: Jakub Jelinek @ 2020-03-25 10:13 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:5f18995e23edc944af3a401d9d9d3320a9362652
commit 5f18995e23edc944af3a401d9d9d3320a9362652
Author: Jakub Jelinek <jakub@redhat.com>
Date: Wed Mar 25 09:21:05 2020 +0100
varasm: Fix output_constructor where a RANGE_EXPR index needs to skip some elts [PR94303]
The following testcase is miscompiled, because output_constructor doesn't
output the initializer correctly. The FE creates {[1...2] = 9} in this
case, and we emit .long 9; long 9; .zero 8 instead of the expected
.zero 8; .long 9; .long 9. If the CONSTRUCTOR is {[1] = 9, [2] = 9},
output_constructor_regular_field has code to notice that the current
location (local->total_bytes) is smaller than the location we want to write
to (1*sizeof(elt)) and will call assemble_zeros to skip those. But
RANGE_EXPRs are handled by a different function which didn't do this,
so for RANGE_EXPRs we emitted them properly only if local->total_bytes
was always equal to the location where the RANGE_EXPR needs to start.
2020-03-25 Jakub Jelinek <jakub@redhat.com>
PR middle-end/94303
* varasm.c (output_constructor_array_range): If local->index
RANGE_EXPR doesn't start at the current location in the constructor,
skip needed number of bytes using assemble_zeros or assert we don't
go backwards.
PR middle-end/94303
* g++.dg/torture/pr94303.C: New test.
Diff:
---
gcc/ChangeLog | 6 ++++++
gcc/testsuite/ChangeLog | 3 +++
gcc/testsuite/g++.dg/torture/pr94303.C | 17 +++++++++++++++++
gcc/varasm.c | 20 ++++++++++++++++++++
4 files changed, 46 insertions(+)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cde4653c030..3a1bfcef39b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,11 @@
2020-03-25 Jakub Jelinek <jakub@redhat.com>
+ PR middle-end/94303
+ * varasm.c (output_constructor_array_range): If local->index
+ RANGE_EXPR doesn't start at the current location in the constructor,
+ skip needed number of bytes using assemble_zeros or assert we don't
+ go backwards.
+
PR c++/94223
* langhooks.c (lhd_set_decl_assembler_name): Use a static ulong
counter instead of DECL_UID.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 048f830409e..b68779ff339 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
2020-03-25 Jakub Jelinek <jakub@redhat.com>
+ PR middle-end/94303
+ * g++.dg/torture/pr94303.C: New test.
+
PR c++/94223
* g++.dg/opt/pr94223.C: New test.
diff --git a/gcc/testsuite/g++.dg/torture/pr94303.C b/gcc/testsuite/g++.dg/torture/pr94303.C
new file mode 100644
index 00000000000..45b90a2249d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr94303.C
@@ -0,0 +1,17 @@
+// PR middle-end/94303
+// { dg-do run }
+
+struct A {
+ int d = 9;
+ A () = default;
+ A (int x) : d(x) {}
+ void foo () { if (d < 1) __builtin_abort (); }
+};
+
+A a[3] = { 1 };
+
+int
+main ()
+{
+ a[2].foo ();
+}
diff --git a/gcc/varasm.c b/gcc/varasm.c
index dc6da6c0b5b..271a67abf56 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -5152,6 +5152,26 @@ struct oc_local_state {
static void
output_constructor_array_range (oc_local_state *local)
{
+ /* Perform the index calculation in modulo arithmetic but
+ sign-extend the result because Ada has negative DECL_FIELD_OFFSETs
+ but we are using an unsigned sizetype. */
+ unsigned prec = TYPE_PRECISION (sizetype);
+ offset_int idx = wi::sext (wi::to_offset (TREE_OPERAND (local->index, 0))
+ - wi::to_offset (local->min_index), prec);
+ tree valtype = TREE_TYPE (local->val);
+ HOST_WIDE_INT fieldpos
+ = (idx * wi::to_offset (TYPE_SIZE_UNIT (valtype))).to_short_addr ();
+
+ /* Advance to offset of this element. */
+ if (fieldpos > local->total_bytes)
+ {
+ assemble_zeros (fieldpos - local->total_bytes);
+ local->total_bytes = fieldpos;
+ }
+ else
+ /* Must not go backwards. */
+ gcc_assert (fieldpos == local->total_bytes);
+
unsigned HOST_WIDE_INT fieldsize
= int_size_in_bytes (TREE_TYPE (local->type));
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