[Mesa-dev] [PATCH 1/3] gallivm: Emit vector selects.

[jfonseca at vmware.com]

From: José Fonseca <jfonseca at vmware.com>

They are supported on LLVM 3.1, at least on x86. (I haven't tested on PPC
though.)

Actually lp_build_linear_mip_levels() already has been emitting them for
some time.

This avoids intrinsics, which tend to be an obstacle for certain
optimization passes.
---
 src/gallium/auxiliary/gallivm/lp_bld_logic.c |   14 ++------------
 1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/src/gallium/auxiliary/gallivm/lp_bld_logic.c b/src/gallium/auxiliary/gallivm/lp_bld_logic.c
index f56b61b..cdb7e0a 100644
--- a/src/gallium/auxiliary/gallivm/lp_bld_logic.c
+++ b/src/gallium/auxiliary/gallivm/lp_bld_logic.c
@@ -458,20 +458,10 @@ lp_build_select(struct lp_build_context *bld,
       mask = LLVMBuildTrunc(builder, mask, LLVMInt1TypeInContext(lc), "");
       res = LLVMBuildSelect(builder, mask, a, b, "");
    }
-   else if (0) {
+   else if (HAVE_LLVM >= 0x301) {
       /* Generate a vector select.
        *
-       * XXX: Using vector selects would avoid emitting intrinsics, but they aren't
-       * properly supported yet.
-       *
-       * LLVM 3.0 includes experimental support provided the -promote-elements
-       * options is passed to LLVM's command line (e.g., via
-       * llvm::cl::ParseCommandLineOptions), but resulting code quality is much
-       * worse, probably because some optimization passes don't know how to
-       * handle vector selects.
-       *
-       * See also:
-       * - http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/043659.html
+       * Only supported on LLVM 3.1 onwards
        */
 
       /* Convert the mask to a vector of booleans.
-- 
1.7.9.5