Mesa (master): llvmpipe: Fallback to element-wise comparisons when no comparison intrinsic is available .
Jose Fonseca
jrfonseca at kemper.freedesktop.org
Mon Aug 31 09:22:42 UTC 2009
Module: Mesa
Branch: master
Commit: 241c3a1d8001fc5a30e2af4b4636b48e6f99690a
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=241c3a1d8001fc5a30e2af4b4636b48e6f99690a
Author: José Fonseca <jfonseca at vmware.com>
Date: Mon Aug 31 10:22:36 2009 +0100
llvmpipe: Fallback to element-wise comparisons when no comparison intrinsic is available.
Although selection of vector elements is valid LLVM IR, no machine target
supports it yet.
This is a last-resort option, but it allows llvmpipe to be used on any
target supported by LLVM without modifications. Obviously better
performance is attainable by emitting SIMD intrinsics where otherwise
LLVM doesn't.
---
src/gallium/drivers/llvmpipe/lp_bld_logic.c | 47 +++++++++++++++++++++++++-
1 files changed, 45 insertions(+), 2 deletions(-)
diff --git a/src/gallium/drivers/llvmpipe/lp_bld_logic.c b/src/gallium/drivers/llvmpipe/lp_bld_logic.c
index d6dfd85..8631efd 100644
--- a/src/gallium/drivers/llvmpipe/lp_bld_logic.c
+++ b/src/gallium/drivers/llvmpipe/lp_bld_logic.c
@@ -51,6 +51,8 @@ lp_build_cmp(struct lp_build_context *bld,
LLVMValueRef zeros = LLVMConstNull(int_vec_type);
LLVMValueRef ones = LLVMConstAllOnes(int_vec_type);
LLVMValueRef cond;
+ LLVMValueRef res;
+ unsigned i;
if(func == PIPE_FUNC_NEVER)
return zeros;
@@ -67,7 +69,6 @@ lp_build_cmp(struct lp_build_context *bld,
LLVMValueRef args[3];
unsigned cc;
boolean swap;
- LLVMValueRef res;
swap = FALSE;
switch(func) {
@@ -218,7 +219,28 @@ lp_build_cmp(struct lp_build_context *bld,
assert(0);
return bld->undef;
}
+
+#if 0
+ /* XXX: Although valid IR, no LLVM target currently support this */
cond = LLVMBuildFCmp(bld->builder, op, a, b, "");
+ res = LLVMBuildSelect(bld->builder, cond, ones, zeros, "");
+#else
+ debug_printf("%s: warning: using slow element-wise vector comparison\n",
+ __FUNCTION__);
+ res = LLVMGetUndef(int_vec_type);
+ for(i = 0; i < type.length; ++i) {
+ LLVMValueRef index = LLVMConstInt(LLVMInt32Type(), i, 0);
+ cond = LLVMBuildFCmp(bld->builder, op,
+ LLVMBuildExtractElement(bld->builder, a, index, ""),
+ LLVMBuildExtractElement(bld->builder, b, index, ""),
+ "");
+ cond = LLVMBuildSelect(bld->builder, cond,
+ LLVMConstExtractElement(ones, index),
+ LLVMConstExtractElement(zeros, index),
+ "");
+ res = LLVMBuildInsertElement(bld->builder, res, cond, index, "");
+ }
+#endif
}
else {
LLVMIntPredicate op;
@@ -245,10 +267,31 @@ lp_build_cmp(struct lp_build_context *bld,
assert(0);
return bld->undef;
}
+
+#if 0
+ /* XXX: Although valid IR, no LLVM target currently support this */
cond = LLVMBuildICmp(bld->builder, op, a, b, "");
+ res = LLVMBuildSelect(bld->builder, cond, ones, zeros, "");
+#else
+ debug_printf("%s: warning: using slow element-wise vector comparison\n",
+ __FUNCTION__);
+ res = LLVMGetUndef(int_vec_type);
+ for(i = 0; i < type.length; ++i) {
+ LLVMValueRef index = LLVMConstInt(LLVMInt32Type(), i, 0);
+ cond = LLVMBuildICmp(bld->builder, op,
+ LLVMBuildExtractElement(bld->builder, a, index, ""),
+ LLVMBuildExtractElement(bld->builder, b, index, ""),
+ "");
+ cond = LLVMBuildSelect(bld->builder, cond,
+ LLVMConstExtractElement(ones, index),
+ LLVMConstExtractElement(zeros, index),
+ "");
+ res = LLVMBuildInsertElement(bld->builder, res, cond, index, "");
+ }
+#endif
}
- return LLVMBuildSelect(bld->builder, cond, ones, zeros, "");
+ return res;
}
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