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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.
This commit is contained in:
José Fonseca 2009-08-31 10:22:36 +01:00
parent 45fb66ab7b
commit 241c3a1d80
1 changed files with 45 additions and 2 deletions
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47
src/gallium/drivers/llvmpipe/lp_bld_logic.c
View File

@ -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;
}