i386: Fix splitters that call extract_insn_cached [PR93611]

The following testcase ICEs.  The generated split_insns starts
with recog_data.insn = NULL and then tries to put various operands into
recog_data.operand array and checks various splitter conditions.
The problem is that some atom related tuning splitters indirectly call
extract_insn_cached on the insn they are used in.  This can change
recog_data.operand, but most likely it will just keep it as is, but
sets recog_data.insn to the current instruction.  If that splitter doesn't
match, we continue trying some other split conditions and modify
recog_data.operand array again.  If even that doesn't find any usable
splitter, we punt, but at that point recog_data.insn says that recog_data
is valid for that particular instruction, even when recog_data.operand array
can be anything.
The safest thing would be to copy whole recog_data to a temporary object
before doing the calls that can call extract_insn_cached and restore it
afterwards, but it would be also very costly, recog_data has 1280 bytes.
So, this patch just makes sure to clear recog_data.insn if it has changed
during the extract_insn_cached call, which means if we extract_insn_cached
later, we'll extract it properly, while if we call it say from some other
context than splitter conditions, the insn is already cached, we don't reset
the cache.

2020-02-07  Jakub Jelinek  <jakub@redhat.com>

	PR target/93611
	* config/i386/i386.c (ix86_lea_outperforms): Make sure to clear
	recog_data.insn if distance_non_agu_define changed it.

	* gcc.target/i386/pr93611.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9797dd4..56090a9 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2020-02-07  Jakub Jelinek  <jakub@redhat.com>
+
+       PR target/93611
+       * config/i386/i386.c (ix86_lea_outperforms): Make sure to clear
+       recog_data.insn if distance_non_agu_define changed it.
+
 2020-02-06  Michael Meissner  <meissner@linux.ibm.com>
 
        PR target/93569

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index ffda3e8..556ca82 100644 (file)
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -14459,9 +14459,18 @@ ix86_lea_outperforms (rtx_insn *insn, unsigned int regno0, unsigned int regno1,
       return true;
     }
 
+  rtx_insn *rinsn = recog_data.insn;
+
   dist_define = distance_non_agu_define (regno1, regno2, insn);
   dist_use = distance_agu_use (regno0, insn);
 
+  /* distance_non_agu_define can call extract_insn_cached.  If this function
+     is called from define_split conditions, that can break insn splitting,
+     because split_insns works by clearing recog_data.insn and then modifying
+     recog_data.operand array and match the various split conditions.  */
+  if (recog_data.insn != rinsn)
+    recog_data.insn = NULL;
+
   if (dist_define < 0 || dist_define >= LEA_MAX_STALL)
     {
       /* If there is no non AGU operand definition, no AGU

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a6fbf5b..6be609a 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2020-02-07  Jakub Jelinek  <jakub@redhat.com>
+
+       PR target/93611
+       * gcc.target/i386/pr93611.c: New test.
+
 2020-02-06  David Malcolm  <dmalcolm@redhat.com>
 
        PR analyzer/93375

diff --git a/gcc/testsuite/gcc.target/i386/pr93611.c b/gcc/testsuite/gcc.target/i386/pr93611.c
new file mode 100644 (file)
index 0000000..2a0e816
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr93611.c
@@ -0,0 +1,5 @@
+/* PR target/93611 */
+/* { dg-do compile } */
+/* { dg-options "-fira-algorithm=priority -O3 -mtune=bonnell" } */
+
+#include "../../gcc.dg/vect/pr58508.c"