[PATCH] rtl-optimization/119689 - compare-debug failure with LRA

[Richard Biener]

The previous change to fix LRA rematerialization broke compare-debug
for i586 bootstrap.  Fixed by using prev_nonnote_nondebug_insn
instead of prev_nonnote_insn.

Bootstrapped on i586-linux where the miscompare is gone with this
patch.  Bootstrap and regtest running on x86_64-unknown-linux-gnu.

OK if the latter succeeds?

Thanks,
Richard.

        PR rtl-optimization/119689
        PR rtl-optimization/115568
        * lra-remat.cc (create_cands): Use prev_nonnote_nondebug_insn
        to check whether insn2 is directly before insn.

        * g++.target/i386/pr119689.C: New testcase.
---
 gcc/lra-remat.cc                         |  2 +-
 gcc/testsuite/g++.target/i386/pr119689.C | 44 ++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.target/i386/pr119689.C

diff --git a/gcc/lra-remat.cc b/gcc/lra-remat.cc
index 2f3afffcf5b..5f823193aa7 100644
--- a/gcc/lra-remat.cc
+++ b/gcc/lra-remat.cc
@@ -460,7 +460,7 @@ create_cands (void)
                && dst_regno >= FIRST_PSEUDO_REGISTER
                && reg_renumber[dst_regno] < 0
                && BLOCK_FOR_INSN (insn2) == BLOCK_FOR_INSN (insn)
-               && insn2 == prev_nonnote_insn (insn))
+               && insn2 == prev_nonnote_nondebug_insn (insn))
              {
                create_cand (insn2, regno_potential_cand[src_regno].nop,
                             dst_regno, insn);
diff --git a/gcc/testsuite/g++.target/i386/pr119689.C 
b/gcc/testsuite/g++.target/i386/pr119689.C
new file mode 100644
index 00000000000..cdc6d2dade5
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr119689.C
@@ -0,0 +1,44 @@
+// { dg-do compile }
+// { dg-options "-O2 -fcompare-debug" }
+// { dg-additional-options "-march=i586 -mtune=generic" { target ia32 } }
+// { dg-additional-options "-fPIC" { target { fpic } } }
+
+enum gimple_code { GIMPLE_ASSIGN, GIMPLE_RETURN };
+bool is_gimple_call();
+int m_sig, m_exp, sreal_new_exp;
+struct sreal {
+  sreal(long long sig) {
+    long long __trans_tmp_6 = sig >= 0 ? sig : -(unsigned long long)sig;
+    sig = __trans_tmp_6 <<= sreal_new_exp -= m_exp = __trans_tmp_6;
+    m_sig = sig;
+  }
+  void operator/(sreal);
+};
+struct ipa_predicate {
+  ipa_predicate(bool = true);
+  void operator&=(ipa_predicate);
+  void operator&(ipa_predicate);
+};
+void add_condition();
+gimple_code eliminated_by_inlining_prob_code;
+static int eliminated_by_inlining_prob() {
+  switch (eliminated_by_inlining_prob_code) {
+  case GIMPLE_RETURN:
+    return 2;
+  case GIMPLE_ASSIGN:
+    return 1;
+  }
+  return 0;
+}
+void fp_expression_p() {
+  ipa_predicate bb_predicate;
+  for (;;) {
+    int prob = eliminated_by_inlining_prob();
+    ipa_predicate sra_predicate;
+    sra_predicate &= add_condition;
+    if (is_gimple_call())
+      sreal(prob) / 2;
+    if (prob != 2)
+      bb_predicate & sra_predicate;
+  }
+}
-- 
2.43.0