[libclc] 11/79: math: Use precomputed constant for log2(10.0)

[Andreas Boll]

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commit d66c58061c51054ccb09cc8b7c9de53a9da295f9
Author: Jan Vesely <jan.vesely at rutgers.edu>
Date:   Mon Nov 13 18:28:45 2017 +0000

    math: Use precomputed constant for log2(10.0)
    
    exp10 CTS fails with or without this change
    
    Reviewer: Jeroen Ketema
    Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
    
    git-svn-id: https://llvm.org/svn/llvm-project/libclc/trunk@318063 91177308-0d34-0410-b5e6-96231b3b80d8
---
 generic/include/clc/float/definitions.h | 8 ++++++++
 generic/lib/math/exp10.inc              | 4 ++--
 generic/lib/math/native_exp10.inc       | 2 +-
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/generic/include/clc/float/definitions.h b/generic/include/clc/float/definitions.h
index 6010ed2..84a102e 100644
--- a/generic/include/clc/float/definitions.h
+++ b/generic/include/clc/float/definitions.h
@@ -31,6 +31,10 @@
 #define M_SQRT2_F       0x1.6a09e6p+0f
 #define M_SQRT1_2_F     0x1.6a09e6p-1f
 
+#ifdef __CLC_INTERNAL
+#define M_LOG210_F      0x1.a934f0p+1f
+#endif
+
 #ifdef cl_khr_fp64
 
 #define HUGE_VAL        __builtin_huge_val()
@@ -59,6 +63,10 @@
 #define M_SQRT2         0x1.6a09e667f3bcdp+0
 #define M_SQRT1_2       0x1.6a09e667f3bcdp-1
 
+#ifdef __CLC_INTERNAL
+#define M_LOG210	0x1.a934f0979a371p+1
+#endif
+
 #endif
 
 #ifdef cl_khr_fp16
diff --git a/generic/lib/math/exp10.inc b/generic/lib/math/exp10.inc
index a592c19..f5482e4 100644
--- a/generic/lib/math/exp10.inc
+++ b/generic/lib/math/exp10.inc
@@ -1,9 +1,9 @@
 _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE exp10(__CLC_GENTYPE val) {
   // exp10(x) = exp2(x * log2(10))
 #if __CLC_FPSIZE == 32
-  return exp2(val * log2(10.0f));
+  return exp2(val * M_LOG210_F);
 #elif __CLC_FPSIZE == 64
-  return exp2(val * log2(10.0));
+  return exp2(val * M_LOG210);
 #else
 #error unknown _CLC_FPSIZE
 #endif
diff --git a/generic/lib/math/native_exp10.inc b/generic/lib/math/native_exp10.inc
index b82a650..9826b4e 100644
--- a/generic/lib/math/native_exp10.inc
+++ b/generic/lib/math/native_exp10.inc
@@ -1,3 +1,3 @@
 _CLC_OVERLOAD _CLC_DEF __CLC_GENTYPE native_exp10(__CLC_GENTYPE val) {
-  return native_exp2(val * native_log2(10));
+  return native_exp2(val * M_LOG210_F);
 }

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