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gallivm: add a log function that handles edge cases

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Same as log2_safe, which means that it can handle infs, 0s and
nans.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
This commit is contained in:
Zack Rusin 2013-07-18 03:32:02 -04:00
parent 018c69ac56
commit f7c06785d0
2 changed files with 21 additions and 0 deletions
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17
src/gallium/auxiliary/gallivm/lp_bld_arit.c
View file

@ -3080,6 +3080,7 @@ lp_build_exp(struct lp_build_context *bld,
/**
* Generate log(x)
* Behavior is undefined with infs, 0s and nans
*/
LLVMValueRef
lp_build_log(struct lp_build_context *bld,
@ -3094,6 +3095,22 @@ lp_build_log(struct lp_build_context *bld,
return lp_build_mul(bld, log2, lp_build_log2(bld, x));
}
/**
* Generate log(x) that handles edge cases (infs, 0s and nans)
*/
LLVMValueRef
lp_build_log_safe(struct lp_build_context *bld,
LLVMValueRef x)
{
/* log(2) */
LLVMValueRef log2 = lp_build_const_vec(bld->gallivm, bld->type,
0.69314718055994529);
assert(lp_check_value(bld->type, x));
return lp_build_mul(bld, log2, lp_build_log2_safe(bld, x));
}
/**
* Generate polynomial.

4
src/gallium/auxiliary/gallivm/lp_bld_arit.h
View file

@ -291,6 +291,10 @@ LLVMValueRef
lp_build_log(struct lp_build_context *bld,
LLVMValueRef a);
LLVMValueRef
lp_build_log_safe(struct lp_build_context *bld,
LLVMValueRef a);
LLVMValueRef
lp_build_exp2(struct lp_build_context *bld,
LLVMValueRef a);