gcc/

2014-08-11  Michael Collison  <michael.collison@linaro.org>

	Backport from trunk r206529, r206530
	2014-01-10  Richard Earnshaw  <rearnsha@arm.com>

	PR target/59744
	* aarch64-modes.def (CC_Zmode): New flags mode.
	* aarch64.c (aarch64_select_cc_mode): Only allow NEG when the condition
	represents an equality.
	(aarch64_get_condition_code): Handle CC_Zmode.
	* aarch64.md (compare_neg<mode>): Restrict to equality operations.

gcc/testsuite/
2014-08-11  Michael Collison  <michael.collison@linaro.org>

	Backport from trunk r206529
	2014-01-10  Richard Earnshaw  <rearnsha@arm.com>

	PR target/59744
	* gcc.target/aarch64/cmn-neg.c: Use equality comparisons.
	* gcc.target/aarch64/cmn-neg2.c: New test.



git-svn-id: https://gcc.gnu.org/svn/gcc/branches/linaro/gcc-4_8-branch@213842 138bc75d-0d04-0410-961f-82ee72b054a4

7 files changed, 79 insertions, 7 deletions

diff --git a/gcc/ChangeLog.linaro b/gcc/ChangeLog.linaro
index 45587a4252b..49f418e1487 100644
--- a/gcc/ChangeLog.linaro
+++ b/gcc/ChangeLog.linaro
@@ -1,5 +1,17 @@
 2014-08-11  Michael Collison  <michael.collison@linaro.org>
 
+	Backport from trunk r206529, r206530
+	2014-01-10  Richard Earnshaw  <rearnsha@arm.com>
+
+	PR target/59744
+	* aarch64-modes.def (CC_Zmode): New flags mode.
+	* aarch64.c (aarch64_select_cc_mode): Only allow NEG when the condition
+	represents an equality.
+	(aarch64_get_condition_code): Handle CC_Zmode.
+	* aarch64.md (compare_neg<mode>): Restrict to equality operations.
+
+2014-08-11  Michael Collison  <michael.collison@linaro.org>
+
 	Backport from trunk r204251
 	2013-10-31  Richard Sandiford  <rsandifo@linux.vnet.ibm.com>
 	Yury Gribov  <y.gribov@samsung.com>
diff --git a/gcc/config/aarch64/aarch64-modes.def b/gcc/config/aarch64/aarch64-modes.def
index fc547c890ea..c7fdddb2c81 100644
--- a/gcc/config/aarch64/aarch64-modes.def
+++ b/gcc/config/aarch64/aarch64-modes.def
@@ -24,6 +24,7 @@ CC_MODE (CC_SWP);
 CC_MODE (CC_ZESWP); /* zero-extend LHS (but swap to make it RHS).  */
 CC_MODE (CC_SESWP); /* sign-extend LHS (but swap to make it RHS).  */
 CC_MODE (CC_NZ);    /* Only N and Z bits of condition flags are valid.  */
+CC_MODE (CC_Z);     /* Only Z bit of condition flags is valid.  */
 
 /* Vector modes.  */
 VECTOR_MODES (INT, 8);        /*       V8QI V4HI V2SI.  */
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index bcad1b924e4..3589f057f78 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -3259,17 +3259,24 @@ aarch64_select_cc_mode (RTX_CODE code, rtx x, rtx y)
 	  || GET_CODE (x) == NEG))
     return CC_NZmode;
 
-  /* A compare with a shifted or negated operand.  Because of canonicalization,
+  /* A compare with a shifted operand.  Because of canonicalization,
      the comparison will have to be swapped when we emit the assembly
      code.  */
   if ((GET_MODE (x) == SImode || GET_MODE (x) == DImode)
       && (GET_CODE (y) == REG || GET_CODE (y) == SUBREG)
       && (GET_CODE (x) == ASHIFT || GET_CODE (x) == ASHIFTRT
 	  || GET_CODE (x) == LSHIFTRT
-	  || GET_CODE (x) == ZERO_EXTEND || GET_CODE (x) == SIGN_EXTEND
-	  || GET_CODE (x) == NEG))
+	  || GET_CODE (x) == ZERO_EXTEND || GET_CODE (x) == SIGN_EXTEND))
     return CC_SWPmode;
 
+  /* Similarly for a negated operand, but we can only do this for
+     equalities.  */
+  if ((GET_MODE (x) == SImode || GET_MODE (x) == DImode)
+      && (GET_CODE (y) == REG || GET_CODE (y) == SUBREG)
+      && (code == EQ || code == NE)
+      && GET_CODE (x) == NEG)
+    return CC_Zmode;
+
   /* A compare of a mode narrower than SI mode against zero can be done
      by extending the value in the comparison.  */
   if ((GET_MODE (x) == QImode || GET_MODE (x) == HImode)
@@ -3360,6 +3367,15 @@ aarch64_get_condition_code (rtx x)
 	}
       break;
 
+    case CC_Zmode:
+      switch (comp_code)
+	{
+	case NE: return AARCH64_NE;
+	case EQ: return AARCH64_EQ;
+	default: gcc_unreachable ();
+	}
+      break;
+
     default:
       gcc_unreachable ();
       break;
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index dea03118bf7..0bf9009d5b4 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -1234,8 +1234,8 @@
 )
 
 (define_insn "*compare_neg<mode>"
-  [(set (reg:CC_SWP CC_REGNUM)
-	(compare:CC_SWP
+  [(set (reg:CC_Z CC_REGNUM)
+	(compare:CC_Z
 	 (neg:GPI (match_operand:GPI 0 "register_operand" "r"))
 	 (match_operand:GPI 1 "register_operand" "r")))]
   ""
diff --git a/gcc/testsuite/ChangeLog.linaro b/gcc/testsuite/ChangeLog.linaro
index 1b9307a0683..a68e21c08e9 100644
--- a/gcc/testsuite/ChangeLog.linaro
+++ b/gcc/testsuite/ChangeLog.linaro
@@ -1,3 +1,12 @@
+2014-08-11  Michael Collison  <michael.collison@linaro.org>
+
+	Backport from trunk r206529
+	2014-01-10  Richard Earnshaw  <rearnsha@arm.com>
+
+	PR target/59744
+	* gcc.target/aarch64/cmn-neg.c: Use equality comparisons.
+	* gcc.target/aarch64/cmn-neg2.c: New test.
+
 2014-04-07  Yvan Roux  <yvan.roux@linaro.org>
 
 	GCC Linaro 4.8-2014.04 released.
diff --git a/gcc/testsuite/gcc.target/aarch64/cmn-neg.c b/gcc/testsuite/gcc.target/aarch64/cmn-neg.c
index 05c8bbff5be..ab264e798ef 100644
--- a/gcc/testsuite/gcc.target/aarch64/cmn-neg.c
+++ b/gcc/testsuite/gcc.target/aarch64/cmn-neg.c
@@ -6,7 +6,7 @@ extern void abort (void);
 void __attribute__ ((noinline))
 foo_s32 (int a, int b)
 {
-  if (a < -b)
+  if (a == -b)
     abort ();
 }
 /* { dg-final { scan-assembler "cmn\tw\[0-9\]" } } */
@@ -14,7 +14,7 @@ foo_s32 (int a, int b)
 void __attribute__ ((noinline))
 foo_s64 (long long a, long long b)
 {
-  if (a < -b)
+  if (a == -b)
     abort ();
 }
 /* { dg-final { scan-assembler "cmn\tx\[0-9\]" } } */
diff --git a/gcc/testsuite/gcc.target/aarch64/cmn-neg2.c b/gcc/testsuite/gcc.target/aarch64/cmn-neg2.c
new file mode 100644
index 00000000000..ca45a53435f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/cmn-neg2.c
@@ -0,0 +1,34 @@
+/* { dg-do run } */
+/* { dg-options "-O2 --save-temps" } */
+
+extern void abort (void);
+
+/* It's unsafe to use CMN in these comparisons.  */
+
+void __attribute__ ((noinline))
+foo_s32 (int a, int b)
+{
+  if (a < -b)
+    abort ();
+}
+
+void __attribute__ ((noinline))
+foo_s64 (unsigned long long a, unsigned long long b)
+{
+  if (a > -b)
+    abort ();
+}
+
+
+int
+main (void)
+{
+  int a = 30;
+  int b = 42;
+  foo_s32 (a, b);
+  foo_s64 (a, b);
+  return 0;
+}
+/* { dg-final { scan-assembler-not "cmn\t" } } */
+
+/* { dg-final { cleanup-saved-temps } } */