diff options
author | Brian Paul <[email protected]> | 2009-09-29 18:57:13 -0600 |
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committer | Brian Paul <[email protected]> | 2009-09-29 18:57:13 -0600 |
commit | 65765c9f2c5d3568608bde57db0bf44d6b724755 (patch) | |
tree | 9825cbfd5c239e2bef19d1ea40b1fc1cb743592c /src/mesa/shader/slang/library | |
parent | 3c794e45b02c66ce3f52fe359f733e4d7d2ce315 (diff) |
glsl: rewrite sqrt(x) intrinsic to handle x=0
Since sqrt() is basically implemented in terms of RSQ/RCP we'll do a
divide by zero if x=0 and wind up with unpredictable results.
Now use CMP instruction to test for x<=0 and return zero in that case.
Diffstat (limited to 'src/mesa/shader/slang/library')
-rw-r--r-- | src/mesa/shader/slang/library/slang_common_builtin.gc | 76 |
1 files changed, 42 insertions, 34 deletions
diff --git a/src/mesa/shader/slang/library/slang_common_builtin.gc b/src/mesa/shader/slang/library/slang_common_builtin.gc index 9764fc25b09..56de47ee8d7 100644 --- a/src/mesa/shader/slang/library/slang_common_builtin.gc +++ b/src/mesa/shader/slang/library/slang_common_builtin.gc @@ -602,42 +602,50 @@ vec4 exp2(const vec4 a) float sqrt(const float x) { + const float nx = -x; float r; __asm float_rsq r, x; - __asm float_rcp __retVal, r; -} - -vec2 sqrt(const vec2 v) -{ - float r; - __asm float_rsq r, v.x; - __asm float_rcp __retVal.x, r; - __asm float_rsq r, v.y; - __asm float_rcp __retVal.y, r; -} - -vec3 sqrt(const vec3 v) -{ - float r; - __asm float_rsq r, v.x; - __asm float_rcp __retVal.x, r; - __asm float_rsq r, v.y; - __asm float_rcp __retVal.y, r; - __asm float_rsq r, v.z; - __asm float_rcp __retVal.z, r; -} - -vec4 sqrt(const vec4 v) -{ - float r; - __asm float_rsq r, v.x; - __asm float_rcp __retVal.x, r; - __asm float_rsq r, v.y; - __asm float_rcp __retVal.y, r; - __asm float_rsq r, v.z; - __asm float_rcp __retVal.z, r; - __asm float_rsq r, v.w; - __asm float_rcp __retVal.w, r; + __asm float_rcp r, r; + __asm vec4_cmp __retVal, nx, r, 0.0; +} + +vec2 sqrt(const vec2 x) +{ + const vec2 nx = -x, zero = vec2(0.0); + vec2 r; + __asm float_rsq r.x, x.x; + __asm float_rsq r.y, x.y; + __asm float_rcp r.x, r.x; + __asm float_rcp r.y, r.y; + __asm vec4_cmp __retVal, nx, r, zero; +} + +vec3 sqrt(const vec3 x) +{ + const vec3 nx = -x, zero = vec3(0.0); + vec3 r; + __asm float_rsq r.x, x.x; + __asm float_rsq r.y, x.y; + __asm float_rsq r.z, x.z; + __asm float_rcp r.x, r.x; + __asm float_rcp r.y, r.y; + __asm float_rcp r.z, r.z; + __asm vec4_cmp __retVal, nx, r, zero; +} + +vec4 sqrt(const vec4 x) +{ + const vec4 nx = -x, zero = vec4(0.0); + vec4 r; + __asm float_rsq r.x, x.x; + __asm float_rsq r.y, x.y; + __asm float_rsq r.z, x.z; + __asm float_rsq r.w, x.w; + __asm float_rcp r.x, r.x; + __asm float_rcp r.y, r.y; + __asm float_rcp r.z, r.z; + __asm float_rcp r.w, r.w; + __asm vec4_cmp __retVal, nx, r, zero; } |