Hello.

Following patch correctly handles builtins mentioned in the email subject
in order to return correct value for 0 as the argument.

The patch can boostrap on x86_64-linux-gnu and survives regression tests and
is pre-approved by Martin Jambor. Moreover, I'm preparing a test-case that
will cover the situation in test-suite.

Installed as r233602.

Thanks,
Martin
>From 7047c51eb08f8d69c3509486fe47c0de8e2fd617 Mon Sep 17 00:00:00 2001
From: marxin <mli...@suse.cz>
Date: Fri, 19 Feb 2016 13:32:42 +0100
Subject: [PATCH 1/3] HSA: fix emission of clrsb{l,ll} builtins

gcc/ChangeLog:

2016-02-19  Martin Liska  <mli...@suse.cz>

	* hsa-gen.c (gen_hsa_clrsb): In case of zero value,
	return bitsize - 1 as the return value.
---
 gcc/hsa-gen.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/gcc/hsa-gen.c b/gcc/hsa-gen.c
index 768c2cf..28e8b6f 100644
--- a/gcc/hsa-gen.c
+++ b/gcc/hsa-gen.c
@@ -4055,7 +4055,9 @@ gen_hsa_clrsb (gcall *call, hsa_bb *hbb)
   hsa_op_with_type *arg = hsa_reg_or_immed_for_gimple_op (rhs1, hbb);
   BrigType16_t bittype = hsa_bittype_for_type (arg->m_type);
   unsigned bitsize = tree_to_uhwi (TYPE_SIZE (TREE_TYPE (rhs1)));
-  gcc_checking_assert (bitsize >= 32);
+
+  /* FIRSTBIT instruction is defined just for 32 and 64-bits wide integers.  */
+  gcc_checking_assert (bitsize == 32 || bitsize == 64);
 
   /* Set true to MOST_SIG if the most significant bit is set to one.  */
   hsa_op_immed *c = new hsa_op_immed (1ul << (bitsize - 1),
@@ -4098,9 +4100,10 @@ gen_hsa_clrsb (gcall *call, hsa_bb *hbb)
 			  new hsa_op_immed (0, arg->m_type));
   hbb->append_insn (cmp);
 
-  /* Return the number of leading bits, or 31 if the input value is zero.  */
+  /* Return the number of leading bits,
+     or (bitsize - 1) if the input value is zero.  */
   cmov = new hsa_insn_basic (4, BRIG_OPCODE_CMOV, BRIG_TYPE_B32, NULL, is_zero,
-			     new hsa_op_immed (31, BRIG_TYPE_U32),
+			     new hsa_op_immed (bitsize - 1, BRIG_TYPE_U32),
 			     leading_bits->get_in_type (BRIG_TYPE_B32, hbb));
   hbb->append_insn (cmov);
   cmov->set_output_in_type (dest, 0, hbb);
-- 
2.7.0

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