Mesa (master): tgsi: obey clarified shift behavior

[Roland Scheidegger]

Module: Mesa
Branch: master
Commit: 7a72bef47e8731276ac4ca0b8c4d6d50366c1ec2
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=7a72bef47e8731276ac4ca0b8c4d6d50366c1ec2

Author: Roland Scheidegger <sroland at vmware.com>
Date:   Tue Jul 30 17:16:17 2013 +0200

tgsi: obey clarified shift behavior

c shifts are undefined for shift counts exceeding (or matching) bit width,
so need to apply a mask (on x86 it actually would usually probably work as
shifts do masking on int domain shifts - unless some auto-vectorizer would
come along at last as simd domain does not mask the shift count).

Reviewed-by: Jose Fonseca <jfonseca at vmware.com>

---

 src/gallium/auxiliary/tgsi/tgsi_exec.c |   39 ++++++++++++++++++++++---------
 1 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/src/gallium/auxiliary/tgsi/tgsi_exec.c b/src/gallium/auxiliary/tgsi/tgsi_exec.c
index 3ac6901..d991d4b 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_exec.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_exec.c
@@ -3198,10 +3198,15 @@ micro_shl(union tgsi_exec_channel *dst,
           const union tgsi_exec_channel *src0,
           const union tgsi_exec_channel *src1)
 {
-   dst->u[0] = src0->u[0] << src1->u[0];
-   dst->u[1] = src0->u[1] << src1->u[1];
-   dst->u[2] = src0->u[2] << src1->u[2];
-   dst->u[3] = src0->u[3] << src1->u[3];
+   unsigned masked_count;
+   masked_count = src1->u[0] & 0x1f;
+   dst->u[0] = src0->u[0] << masked_count;
+   masked_count = src1->u[1] & 0x1f;
+   dst->u[1] = src0->u[1] << masked_count;
+   masked_count = src1->u[2] & 0x1f;
+   dst->u[2] = src0->u[2] << masked_count;
+   masked_count = src1->u[3] & 0x1f;
+   dst->u[3] = src0->u[3] << masked_count;
 }
 
 static void
@@ -3307,10 +3312,15 @@ micro_ishr(union tgsi_exec_channel *dst,
            const union tgsi_exec_channel *src0,
            const union tgsi_exec_channel *src1)
 {
-   dst->i[0] = src0->i[0] >> src1->i[0];
-   dst->i[1] = src0->i[1] >> src1->i[1];
-   dst->i[2] = src0->i[2] >> src1->i[2];
-   dst->i[3] = src0->i[3] >> src1->i[3];
+   unsigned masked_count;
+   masked_count = src1->i[0] & 0x1f;
+   dst->i[0] = src0->i[0] >> masked_count;
+   masked_count = src1->i[1] & 0x1f;
+   dst->i[1] = src0->i[1] >> masked_count;
+   masked_count = src1->i[2] & 0x1f;
+   dst->i[2] = src0->i[2] >> masked_count;
+   masked_count = src1->i[3] & 0x1f;
+   dst->i[3] = src0->i[3] >> masked_count;
 }
 
 static void
@@ -3449,10 +3459,15 @@ micro_ushr(union tgsi_exec_channel *dst,
            const union tgsi_exec_channel *src0,
            const union tgsi_exec_channel *src1)
 {
-   dst->u[0] = src0->u[0] >> src1->u[0];
-   dst->u[1] = src0->u[1] >> src1->u[1];
-   dst->u[2] = src0->u[2] >> src1->u[2];
-   dst->u[3] = src0->u[3] >> src1->u[3];
+   unsigned masked_count;
+   masked_count = src1->u[0] & 0x1f;
+   dst->u[0] = src0->u[0] >> masked_count;
+   masked_count = src1->u[1] & 0x1f;
+   dst->u[1] = src0->u[1] >> masked_count;
+   masked_count = src1->u[2] & 0x1f;
+   dst->u[2] = src0->u[2] >> masked_count;
+   masked_count = src1->u[3] & 0x1f;
+   dst->u[3] = src0->u[3] >> masked_count;
 }
 
 static void