gcc/

	Backport from trunk r239919.
	2016-09-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* config/aarch64/aarch64.md (*ands<mode>_compare0): New pattern.
	* config/aarch64/aarch64.c (aarch64_select_cc_mode): Return CC_NZmode
	for comparisons of integer ZERO_EXTEND against zero.

	gcc/testsuite/
	Backport from trunk r239919.
	2016-09-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* gcc.target/aarch64/ands_3.c: New test.

Change-Id: I1eb5eee3b585ebfac952786043dbd6aed6c3f953

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 24ec578..3cd9d7e 100644 (file)
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -4239,6 +4239,14 @@ aarch64_select_cc_mode (RTX_CODE code, rtx x, rtx y)
       && (GET_MODE (x) == HImode || GET_MODE (x) == QImode))
     return CC_NZmode;
 
+  /* Similarly, comparisons of zero_extends from shorter modes can
+     be performed using an ANDS with an immediate mask.  */
+  if (y == const0_rtx && GET_CODE (x) == ZERO_EXTEND
+      && (GET_MODE (x) == SImode || GET_MODE (x) == DImode)
+      && (GET_MODE (XEXP (x, 0)) == HImode || GET_MODE (XEXP (x, 0)) == QImode)
+      && (code == EQ || code == NE))
+    return CC_NZmode;
+
   if ((GET_MODE (x) == SImode || GET_MODE (x) == DImode)
       && y == const0_rtx
       && (code == EQ || code == NE || code == LT || code == GE)

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 3532788..d916f91 100644 (file)
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -3811,6 +3811,18 @@
   [(set_attr "type" "alus_imm")]
 )
 
+(define_insn "*ands<mode>_compare0"
+  [(set (reg:CC_NZ CC_REGNUM)
+       (compare:CC_NZ
+        (zero_extend:GPI (match_operand:SHORT 1 "register_operand" "r"))
+        (const_int 0)))
+   (set (match_operand:GPI 0 "register_operand" "=r")
+       (zero_extend:GPI (match_dup 1)))]
+  ""
+  "ands\\t%<GPI:w>0, %<GPI:w>1, <short_mask>"
+  [(set_attr "type" "alus_imm")]
+)
+
 (define_insn "*and<mode>3nr_compare0"
   [(set (reg:CC_NZ CC_REGNUM)
        (compare:CC_NZ

diff --git a/gcc/testsuite/gcc.target/aarch64/ands_3.c b/gcc/testsuite/gcc.target/aarch64/ands_3.c
new file mode 100644 (file)
index 0000000..42cb7f0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/ands_3.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+int
+f9 (unsigned char x, int y)
+{
+  if (y > 1 && x == 0)
+    return 10;
+  return x;
+}
+
+/* { dg-final { scan-assembler "ands\t(x|w)\[0-9\]+,\[ \t\]*(x|w)\[0-9\]+,\[ \t\]*255" } } */