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tree-optimization/111807 - ICE in verify_sra_access_forest

Message ID 20231016110256.D4FF03858422@sourceware.org
State Accepted
Headers
Series tree-optimization/111807 - ICE in verify_sra_access_forest |

Checks

Context Check Description
snail/gcc-patch-check success Github commit url

Commit Message

Richard Biener Oct. 16, 2023, 11:02 a.m. UTC 
  The following addresses build_reconstructed_reference failing to
build references with a different offset than the models and thus
the caller conditional being off.  This manifests when attempting
to build a ref with offset 160 from the model BIT_FIELD_REF <l_4827[9], 8, 0>
onto the same base l_4827 but the models offset being 288.  This
cannot work for any kind of ref I can think of, not just with
BIT_FIELD_REFs.

Bootstrapped and tested on x86_64-unknown-linux-gnu, will push
later.

Martin - do you remember which case was supposed to be allowed
with offset < model->offset?

Thanks,
Richard.

	PR tree-optimization/111807
	* tree-sra.cc (build_ref_for_model): Only call
	build_reconstructed_reference when the offsets are the same.

	* gcc.dg/torture/pr111807.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr111807.c | 12 ++++++++++++
 gcc/tree-sra.cc                         |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr111807.c
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Patch

diff --git a/gcc/testsuite/gcc.dg/torture/pr111807.c b/gcc/testsuite/gcc.dg/torture/pr111807.c
new file mode 100644
index 00000000000..09fbdcfb667
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr111807.c
@@ -0,0 +1,12 @@ 
+/* { dg-do compile } */
+
+static struct A {
+  int x : 4;
+} a;
+static int b;
+int main()
+{
+  struct A t[2];
+  t[0] = b ? t[1] : a;
+  return (b ? t[1].x : 0) && 1;
+}
diff --git a/gcc/tree-sra.cc b/gcc/tree-sra.cc
index 24d0c20da6a..f8dff8b27d7 100644
--- a/gcc/tree-sra.cc
+++ b/gcc/tree-sra.cc
@@ -1751,7 +1751,7 @@  build_ref_for_model (location_t loc, tree base, HOST_WIDE_INT offset,
 	  && !TREE_THIS_VOLATILE (base)
 	  && (TYPE_ADDR_SPACE (TREE_TYPE (base))
 	      == TYPE_ADDR_SPACE (TREE_TYPE (model->expr)))
-	  && offset <= model->offset
+	  && offset == model->offset
 	  /* build_reconstructed_reference can still fail if we have already
 	     massaged BASE because of another type incompatibility.  */
 	  && (res = build_reconstructed_reference (loc, base, model)))