arm.c (arm_rtx_costs_internal): Make sdiv more expensive than udiv.

2017-06-09  Tamar Christina  <tamar.christina@arm.com>

	* config/arm/arm.c (arm_rtx_costs_internal): Make sdiv more expensive than udiv.

gcc/testsuite/
2017-06-09  Tamar Christina  <tamar.christina@arm.com>

	* gcc.target/arm/sdiv_costs_1.c: New.

From-SVN: r249062

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c61cba3..d4d2c11 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2017-06-09  Tamar Christina  <tamar.christina@arm.com>
+
+       * config/arm/arm.c (arm_rtx_costs_internal): Make sdiv more expensive than udiv.
+
 2017-06-09  Tom de Vries  <tom@codesourcery.com>
 
        PR target/80855

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 2604102..259597d 100644 (file)
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -9315,6 +9315,10 @@ arm_rtx_costs_internal (rtx x, enum rtx_code code, enum rtx_code outer_code,
        *cost += COSTS_N_INSNS (speed_p ? extra_cost->mult[0].idiv : 0);
       else
        *cost = LIBCALL_COST (2);
+
+      /* Make the cost of sdiv more expensive so when both sdiv and udiv are
+        possible udiv is prefered.  */
+      *cost += (code == DIV ? COSTS_N_INSNS (1) : 0);
       return false;    /* All arguments must be in registers.  */
 
     case MOD:
@@ -9337,7 +9341,9 @@ arm_rtx_costs_internal (rtx x, enum rtx_code code, enum rtx_code outer_code,
 
     /* Fall-through.  */
     case UMOD:
-      *cost = LIBCALL_COST (2);
+      /* Make the cost of sdiv more expensive so when both sdiv and udiv are
+        possible udiv is prefered.  */
+      *cost = LIBCALL_COST (2) + (code == MOD ? COSTS_N_INSNS (1) : 0);
       return false;    /* All arguments must be in registers.  */
 
     case ROTATE:

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 431e2e8..01f2d18 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2017-06-09  Tamar Christina  <tamar.christina@arm.com>
+
+       * gcc.target/arm/sdiv_costs_1.c: New.
+
 2017-06-09  Tom de Vries  <tom@codesourcery.com>
 
        PR target/80855

diff --git a/gcc/testsuite/gcc.target/arm/sdiv_costs_1.c b/gcc/testsuite/gcc.target/arm/sdiv_costs_1.c
new file mode 100644 (file)
index 0000000..76086ab
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/sdiv_costs_1.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -march=armv8-a" } */
+
+/* Both sdiv and udiv can be used here, so prefer udiv.  */
+int f1 (unsigned char *p)
+{
+  return 100 / p[1];
+}
+
+int f2 (unsigned char *p, unsigned short x)
+{
+  return x / p[0];
+}
+
+int f3 (unsigned char *p, int x)
+{
+  x &= 0x7fffffff;
+  return x / p[0];
+}
+
+int f5 (unsigned char *p, unsigned short x)
+{
+  return x % p[0];
+}
+
+/* This should only generate signed divisions.  */
+int f4 (unsigned char *p)
+{
+  return -100 / p[1];
+}
+
+int f6 (unsigned char *p, short x)
+{
+  return x % p[0];
+}
+
+/* { dg-final { scan-assembler-times "udiv\tr\[0-9\]+, r\[0-9\]+, r\[0-9\]+" 4 } } */
+/* { dg-final { scan-assembler-times "sdiv\tr\[0-9\]+, r\[0-9\]+, r\[0-9\]+" 2 } } */