Mesa (master): util/pstipple: stronger guard against no free samplers (v2)

[Nicolai Hähnle]

Module: Mesa
Branch: master
Commit: 040f5cb09edef9b54510ca4b41c44f59a1f01fc3
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=040f5cb09edef9b54510ca4b41c44f59a1f01fc3

Author: Nicolai Hähnle <nicolai.haehnle at amd.com>
Date:   Wed Apr  6 12:57:51 2016 -0500

util/pstipple: stronger guard against no free samplers (v2)

When hasFixedUnit is false, polygon stippling will fail when there is no free
sampler available. Make the corresponding guard more robust in preparation
of raising PIPE_MAX_SAMPLERS to 32.

The literal 1 is a (signed) int, and shifting into the sign bit is undefined
in C, so change occurences of 1 to 1u.

v2: add an assert for bitfield size and use 1u << idx

Reviewed-by: Brian Paul <brianp at vmware.com>
Reviewed-by: Roland Scheidegger <sroland at vmware.com> (v1)
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl> (v1)
Reviewed-by: Marek Olšák <marek.olsak at amd.com> (v1)

---

 src/gallium/auxiliary/util/u_pstipple.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/gallium/auxiliary/util/u_pstipple.c b/src/gallium/auxiliary/util/u_pstipple.c
index bcbe2a2..3ae8923 100644
--- a/src/gallium/auxiliary/util/u_pstipple.c
+++ b/src/gallium/auxiliary/util/u_pstipple.c
@@ -204,7 +204,7 @@ pstip_transform_decl(struct tgsi_transform_context *ctx,
    if (decl->Declaration.File == TGSI_FILE_SAMPLER) {
       uint i;
       for (i = decl->Range.First; i <= decl->Range.Last; i++) {
-         pctx->samplersUsed |= 1 << i;
+         pctx->samplersUsed |= 1u << i;
       }
    }
    else if (decl->Declaration.File == pctx->wincoordFile) {
@@ -266,9 +266,11 @@ pstip_transform_prolog(struct tgsi_transform_context *ctx)
    int texTemp;
    int sampIdx;
 
+   STATIC_ASSERT(sizeof(pctx->samplersUsed) * 8 >= PIPE_MAX_SAMPLERS);
+
    /* find free texture sampler */
    pctx->freeSampler = free_bit(pctx->samplersUsed);
-   if (pctx->freeSampler >= PIPE_MAX_SAMPLERS)
+   if (pctx->freeSampler < 0 || pctx->freeSampler >= PIPE_MAX_SAMPLERS)
       pctx->freeSampler = PIPE_MAX_SAMPLERS - 1;
 
    if (pctx->wincoordInput < 0)