native_powr: Switch implementation to native_exp2 and native_log2

v2: don't use assume
    check only for x<0, the other conditions are handled transparently
v3: don't check inputs at all, nan propagation works as expected

Reviewer: Jeroen Ketema
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
llvm-svn: 318204

4 files changed, 18 insertions, 1 deletions

diff --git a/libclc/generic/include/clc/math/native_powr.h b/libclc/generic/include/clc/math/native_powr.h
index e8a37d9cb06..c31161a18c0 100644
--- a/libclc/generic/include/clc/math/native_powr.h
+++ b/libclc/generic/include/clc/math/native_powr.h
@@ -1 +1,7 @@
-#define native_powr pow
+#define __CLC_BODY <clc/math/binary_decl_tt.inc>
+#define __CLC_FUNCTION native_powr
+
+#include <clc/math/gentype.inc>
+
+#undef __CLC_BODY
+#undef __CLC_FUNCTION
diff --git a/libclc/generic/lib/SOURCES b/libclc/generic/lib/SOURCES
index 355741c8756..ad5a7437021 100644
--- a/libclc/generic/lib/SOURCES
+++ b/libclc/generic/lib/SOURCES
@@ -127,6 +127,7 @@ math/native_exp2.cl
 math/native_log.cl
 math/native_log10.cl
 math/native_log2.cl
+math/native_powr.cl
 math/native_recip.cl
 math/native_rsqrt.cl
 math/native_sin.cl
diff --git a/libclc/generic/lib/math/native_powr.cl b/libclc/generic/lib/math/native_powr.cl
new file mode 100644
index 00000000000..452bc6fdfea
--- /dev/null
+++ b/libclc/generic/lib/math/native_powr.cl
@@ -0,0 +1,5 @@
+#include <clc/clc.h>
+
+#define __CLC_BODY <native_powr.inc>
+#define __FLOAT_ONLY
+#include <clc/math/gentype.inc>
diff --git a/libclc/generic/lib/math/native_powr.inc b/libclc/generic/lib/math/native_powr.inc
new file mode 100644
index 00000000000..f2c30a9cb5e
--- /dev/null
+++ b/libclc/generic/lib/math/native_powr.inc
@@ -0,0 +1,5 @@
+_CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE native_powr(__CLC_GENTYPE x, __CLC_GENTYPE y) {
+  // x^y == 2^{log2 x^y} == 2^{y * log2 x}
+  // for x < 0 propagate nan created by log2
+  return native_exp2(y * native_log2(x));
+}