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[PATCH][AArch64][2/2] Add rtx cost function handling of clz, clrsb, rbit

Hi all,

Following up on patch "[1/2] Remove UNSPEC_CLS and use clrsb RTL code in its' place" this patch adds rtx costs handling of the CLZ, CLRSB RTL codes as well as the UNSPEC_RBIT unspec.

The CLZ and CLRSB cases are handled identically (they are implemented by the clz and cls instructions respectively).

Bootstrapped and tested on aarch64-linux.

Ok for trunk?


2014-07-22  Kyrylo Tkachov  <>

	* config/aarch64/aarch64.c (aarch64_rtx_costs): Handle CLRSB, CLZ.
	(case UNSPEC): Handle UNSPEC_RBIT.
commit 8f54ebbfb9622dc53c30db11fdcd4d4602aa9d69
Author: Kyrylo Tkachov <>
Date:   Tue Jul 15 15:10:19 2014 +0100

    [AArch64] RTX cost handling for clz, rbit, cls

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 9f42e20..7f67b6a 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -5154,6 +5154,13 @@ aarch64_rtx_costs (rtx x, int code, int outer ATTRIBUTE_UNUSED,
       return false;
+    case CLRSB:
+    case CLZ:
+      if (speed)
+        *cost += extra_cost->alu.clz;
+      return false;
     case COMPARE:
       op0 = XEXP (x, 0);
       op1 = XEXP (x, 1);
@@ -5799,6 +5806,14 @@ cost_plus:
           return false;
+      if (XINT (x, 1) == UNSPEC_RBIT)
+        {
+          if (speed)
+            *cost += extra_cost->alu.rev;
+          return false;
+        }
     case TRUNCATE:

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