From: Bernd Schmidt <bernds@redhat.com>
Date: Mon, 7 Nov 2016 16:59:11 +0000 (+0000)
Subject: re PR tree-optimization/77309 (wrong code at -Os and above on x86_64-linux-gnu (in... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=caa024ffce186dc6ce7ee8217d5d50d7f9a091e0;p=gcc.git

re PR tree-optimization/77309 (wrong code at -Os and above on x86_64-linux-gnu (in the 64-bit mode))

	PR rtl-optimization/77309
	* combine.c (make_compound_operation): Allow EQ for IN_CODE, and
	don't assume an equality comparison for plain COMPARE.
	(simplify_comparison): Pass a more accurate code to
	make_compound_operation.

testsuite/
	PR rtl-optimization/77309
	* gcc.dg/torture/pr77309.c: New test.

From-SVN: r241912
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c237044b0dd..1d1cbb719f9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2016-11-07  Bernd Schmidt  <bschmidt@redhat.com>
+
+	PR rtl-optimization/77309
+	* combine.c (make_compound_operation): Allow EQ for IN_CODE, and
+	don't assume an equality comparison for plain COMPARE.
+	(simplify_comparison): Pass a more accurate code to
+	make_compound_operation.
+
 2016-11-07  Pat Haugen  <pthaugen@us.ibm.com>
 
 	* target.def (compute_pressure_classes): New target hook.
diff --git a/gcc/combine.c b/gcc/combine.c
index f7728783c51..69020561c31 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -7753,7 +7753,8 @@ extract_left_shift (rtx x, int count)
 
    IN_CODE says what kind of expression we are processing.  Normally, it is
    SET.  In a memory address it is MEM.  When processing the arguments of
-   a comparison or a COMPARE against zero, it is COMPARE.  */
+   a comparison or a COMPARE against zero, it is COMPARE, or EQ if more
+   precisely it is an equality comparison against zero.  */
 
 rtx
 make_compound_operation (rtx x, enum rtx_code in_code)
@@ -7767,6 +7768,7 @@ make_compound_operation (rtx x, enum rtx_code in_code)
   rtx new_rtx = 0;
   rtx tem;
   const char *fmt;
+  bool equality_comparison = false;
 
   /* PR rtl-optimization/70944.  */
   if (VECTOR_MODE_P (mode))
@@ -7776,6 +7778,11 @@ make_compound_operation (rtx x, enum rtx_code in_code)
      address, we stay there.  If we have a comparison, set to COMPARE,
      but once inside, go back to our default of SET.  */
 
+  if (in_code == EQ)
+    {
+      equality_comparison = true;
+      in_code = COMPARE;
+    }
   next_code = (code == MEM ? MEM
 	       : ((code == COMPARE || COMPARISON_P (x))
 		  && XEXP (x, 1) == const0_rtx) ? COMPARE
@@ -7984,11 +7991,12 @@ make_compound_operation (rtx x, enum rtx_code in_code)
       /* If we are in a comparison and this is an AND with a power of two,
 	 convert this into the appropriate bit extract.  */
       else if (in_code == COMPARE
-	       && (i = exact_log2 (UINTVAL (XEXP (x, 1)))) >= 0)
+	       && (i = exact_log2 (UINTVAL (XEXP (x, 1)))) >= 0
+	       && (equality_comparison || i < GET_MODE_PRECISION (mode) - 1))
 	new_rtx = make_extraction (mode,
-			       make_compound_operation (XEXP (x, 0),
-							next_code),
-			       i, NULL_RTX, 1, 1, 0, 1);
+				   make_compound_operation (XEXP (x, 0),
+							    next_code),
+				   i, NULL_RTX, 1, 1, 0, 1);
 
       /* If the one operand is a paradoxical subreg of a register or memory and
 	 the constant (limited to the smaller mode) has only zero bits where
@@ -12473,7 +12481,11 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
      We can never remove a SUBREG for a non-equality comparison because
      the sign bit is in a different place in the underlying object.  */
 
-  op0 = make_compound_operation (op0, op1 == const0_rtx ? COMPARE : SET);
+  rtx_code op0_mco_code = SET;
+  if (op1 == const0_rtx)
+    op0_mco_code = code == NE || code == EQ ? EQ : COMPARE;
+
+  op0 = make_compound_operation (op0, op0_mco_code);
   op1 = make_compound_operation (op1, SET);
 
   if (GET_CODE (op0) == SUBREG && subreg_lowpart_p (op0)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 716e6e23500..6e12b1ab86e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-11-07  Bernd Schmidt  <bschmidt@redhat.com>
+
+	PR rtl-optimization/77309
+	* gcc.dg/torture/pr77309.c: New test.
+
 2016-11-07  Jakub Jelinek  <jakub@redhat.com>
 
 	PR middle-end/71529
diff --git a/gcc/testsuite/gcc.dg/torture/pr77309.c b/gcc/testsuite/gcc.dg/torture/pr77309.c
new file mode 100644
index 00000000000..5bdbc0a0b83
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr77309.c
@@ -0,0 +1,14 @@
+/* { dg-do run } */
+
+int a, b;
+
+int main ()
+{
+  long c = 1 % (2 ^ b);
+  c = -c & ~(~(b ^ ~b) || a);
+
+  if (c >= 0)
+    __builtin_abort ();
+
+  return 0;
+}