From: Segher Boessenkool <segher@kernel.crashing.org>
Date: Wed, 3 Dec 2014 06:00:54 +0000 (+0100)
Subject: re PR rtl-optimization/52714 (ICE in fixup_reorder_chain, at cfglayout.c:880)
X-Git-Tag: releases/gcc-5.1.0~2655
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=17adbcebf01689d2f2c5386845398d9aedbe4cb3;p=thirdparty%2Fgcc.git

re PR rtl-optimization/52714 (ICE in fixup_reorder_chain, at cfglayout.c:880)

	PR rtl-optimization/52714
	* combine.c (try_combine): Allow combining two insns into two
	new insns if at least one of those is a noop.

gcc/testsuite/
	* gcc.target/m68k/pr52714.c: New testcase.

From-SVN: r218302
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cfc662879793..e3b3477e5417 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2014-12-03  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/52714
+	* combine.c (try_combine): Allow combining two insns into two
+	new insns if at least one of those is a noop.
+
 2014-12-03  Bin Cheng  <bin.cheng@arm.com>
 
 	* target.def (fusion_priority): Wrap code with @smallexample.
diff --git a/gcc/combine.c b/gcc/combine.c
index 63c1e4f3f603..e6deb4199873 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3812,15 +3812,20 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn *i1, rtx_insn *i0,
   /* Similarly, check for a case where we have a PARALLEL of two independent
      SETs but we started with three insns.  In this case, we can do the sets
      as two separate insns.  This case occurs when some SET allows two
-     other insns to combine, but the destination of that SET is still live.  */
+     other insns to combine, but the destination of that SET is still live.
 
-  else if (i1 && insn_code_number < 0 && asm_noperands (newpat) < 0
+     Also do this if we started with two insns and (at least) one of the
+     resulting sets is a noop; this noop will be deleted later.  */
+
+  else if (insn_code_number < 0 && asm_noperands (newpat) < 0
 	   && GET_CODE (newpat) == PARALLEL
 	   && XVECLEN (newpat, 0) == 2
 	   && GET_CODE (XVECEXP (newpat, 0, 0)) == SET
+	   && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
+	   && (i1 || set_noop_p (XVECEXP (newpat, 0, 0))
+		  || set_noop_p (XVECEXP (newpat, 0, 1)))
 	   && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != ZERO_EXTRACT
 	   && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 0))) != STRICT_LOW_PART
-	   && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
 	   && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT
 	   && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART
 	   && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 1)),
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f2e54ef42153..ee812d25be8e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-12-03  Segher Boessenkool  <segher.kernel.crashing.org>
+
+	PR rtl-optimization/52714
+	* gcc.target/m68k/pr52714.c: New testcase.
+
 2014-12-02  Uros Bizjak  <ubizjak@gmail.com>
 
 	* gcc.target/i386/avx512ifma-vpmaddhuq-2.c: Define AVX512IFMA.
diff --git a/gcc/testsuite/gcc.target/m68k/pr52714.c b/gcc/testsuite/gcc.target/m68k/pr52714.c
new file mode 100644
index 000000000000..0a52a1d4d3aa
--- /dev/null
+++ b/gcc/testsuite/gcc.target/m68k/pr52714.c
@@ -0,0 +1,33 @@
+/* PR rtl-optimization/52714
+
+   Check that combine manages to remove the "stack == 0" test.
+   Without ICEing.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+int __re_compile_fastmap(unsigned char *p)
+{
+    unsigned char **stack;
+    unsigned size;
+    unsigned avail;
+
+    stack = __builtin_alloca(5 * sizeof(unsigned char*));
+    if (stack == 0)
+	return -2;
+    size = 5;
+    avail = 0;
+
+    for (;;) {
+	switch (*p++) {
+	case 0:
+	    if (avail == size)
+		return -2;
+	    stack[avail++] = p;
+	}
+    }
+
+    return 0;
+}
+
+/* { dg-final { scan-assembler-not {\mtst\.l %sp\M} } } */