aarch64: Fix early RA handling of deleted insns [PR113094]

The testcase constructs a sequence of insns that are fully dead
and yet (due to forced options) are not removed as such.  This
triggered a case where we would emit a meaningless reload for a
to-be-deleted insn.

We can't delete the insns first because that might disrupt the
iteration ranges.  So this patch turns them into notes before
the walk and then continues to delete them properly afterwards.

gcc/
	PR target/113094
	* config/aarch64/aarch64-early-ra.cc (apply_allocation): Stub
	out instructions that are going to be deleted before iterating
	over the rest.

gcc/testsuite/
	PR target/113094
	* gcc.target/aarch64/pr113094.c: New test.

diff --git a/gcc/config/aarch64/aarch64-early-ra.cc b/gcc/config/aarch64/aarch64-early-ra.cc
index 24415bd829c2bcd565b8479076c95eb60aeac137..5d2da3e111080179a2eeaeab9b523917418fe368 100644 (file)
--- a/gcc/config/aarch64/aarch64-early-ra.cc
+++ b/gcc/config/aarch64/aarch64-early-ra.cc
@@ -3210,6 +3210,9 @@ early_ra::maybe_convert_to_strided_access (rtx_insn *insn)
 void
 early_ra::apply_allocation ()
 {
+  for (auto *insn : m_dead_insns)
+    set_insn_deleted (insn);
+
   rtx_insn *prev;
   for (auto insn_range : m_insn_ranges)
     for (rtx_insn *insn = insn_range.first;

diff --git a/gcc/testsuite/gcc.target/aarch64/pr113094.c b/gcc/testsuite/gcc.target/aarch64/pr113094.c
new file mode 100644 (file)
index 0000000..b79e1f7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/pr113094.c
@@ -0,0 +1,10 @@
+/* { dg-options "-fno-tree-dse -Ofast -fno-tree-coalesce-vars -fno-dce -fno-tree-dce" } */
+
+struct TV4 {
+  __attribute__((vector_size(sizeof(int) * 4))) int v;
+};
+void modify() {
+  struct TV4 __trans_tmp_1, temp;
+  temp.v[0] = temp.v[3] = 0;
+  __trans_tmp_1 = temp;
+}