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.
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 @@
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 @@
LLVMValueRef args[3];
unsigned cc;
boolean swap;
- LLVMValueRef res;
swap = FALSE;
switch(func) {
@@ -218,7 +219,28 @@
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 @@
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;
}