glsl: Use M_LOG2E constant instead of calling log2

diff --git a/src/glsl/lower_instructions.cpp b/src/glsl/lower_instructions.cpp
index d460ba1a97abd2d3fe00f368c2ef5eba4f0e7d55..0d9374d73bd74f04cf80a239a07ac44e36391924 100644 (file)
--- a/src/glsl/lower_instructions.cpp
+++ b/src/glsl/lower_instructions.cpp
@@ -70,7 +70,7 @@
  * opportunity to do things like constant fold the (1.0 / op1) easily.
  */
 
-#include "main/core.h" /* for M_E */
+#include "main/core.h" /* for M_LOG2E */
 #include "glsl_types.h"
 #include "ir.h"
 #include "ir_optimization.h"
@@ -172,7 +172,7 @@ lower_instructions_visitor::div_to_mul_rcp(ir_expression *ir)
 void
 lower_instructions_visitor::exp_to_exp2(ir_expression *ir)
 {
-   ir_constant *log2_e = new(ir) ir_constant(log2f(M_E));
+   ir_constant *log2_e = new(ir) ir_constant(float(M_LOG2E));
 
    ir->operation = ir_unop_exp2;
    ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[0]->type,
@@ -186,7 +186,7 @@ lower_instructions_visitor::log_to_log2(ir_expression *ir)
    ir->operation = ir_binop_mul;
    ir->operands[0] = new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,
                                           ir->operands[0], NULL);
-   ir->operands[1] = new(ir) ir_constant(1.0f / log2f(M_E));
+   ir->operands[1] = new(ir) ir_constant(float(1.0 / M_LOG2E));
    this->progress = true;
 }
 

diff --git a/src/mesa/main/compiler.h b/src/mesa/main/compiler.h
index 800eb839005bebadf19e15da34a13f31a224370a..5557a3b5cb5ac4ffd804bb27d84ee22d389dc6c6 100644 (file)
--- a/src/mesa/main/compiler.h
+++ b/src/mesa/main/compiler.h
@@ -358,6 +358,10 @@ static INLINE GLuint CPU_TO_LE32(GLuint x)
 #define M_E (2.7182818284590452354)
 #endif
 
+#ifndef M_LOG2E
+#define M_LOG2E     (1.4426950408889634074)
+#endif
+
 #ifndef ONE_DIV_LN2
 #define ONE_DIV_LN2 (1.442695040888963456)
 #endif