From 0630bf9a6254de8ec69ef144d11d9ed4a432453c Mon Sep 17 00:00:00 2001
From: Robert Stepinski <rob.stepinski@gmail.com>
Date: Wed, 6 Mar 2019 21:45:37 -0500
Subject: Fix rsqrt intrinsic for GLSL (#881)

* Add support for glsl inversesqrt intrinsic

* fixup for test failure
---
 source/slang/hlsl.meta.slang                   | 14 +++++++++++---
 source/slang/hlsl.meta.slang.h                 | 14 +++++++++++---
 tests/bugs/vk-structured-buffer-load.hlsl      |  3 ++-
 tests/bugs/vk-structured-buffer-load.hlsl.glsl | 10 +++++++---
 4 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang
index 4135a9051..4044600aa 100644
--- a/source/slang/hlsl.meta.slang
+++ b/source/slang/hlsl.meta.slang
@@ -1156,9 +1156,17 @@ __generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> round(vector<
 __generic<T : __BuiltinFloatingPointType, let N : int, let M : int> matrix<T,N,M> round(matrix<T,N,M> x);
 
 // Reciprocal of square root
-__generic<T : __BuiltinFloatingPointType> T rsqrt(T x);
-__generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> rsqrt(vector<T,N> x);
-__generic<T : __BuiltinFloatingPointType, let N : int, let M : int> matrix<T,N,M> rsqrt(matrix<T,N,M> x);
+__generic<T : __BuiltinFloatingPointType>
+__target_intrinsic(glsl, "inversesqrt($0)")
+T rsqrt(T x);
+
+__generic<T : __BuiltinFloatingPointType, let N : int>
+__target_intrinsic(glsl, "inversesqrt($0)")
+vector<T,N> rsqrt(vector<T,N> x);
+
+__generic<T : __BuiltinFloatingPointType, let N : int, let M : int>
+__target_intrinsic(glsl, "inversesqrt($0)")
+matrix<T,N,M> rsqrt(matrix<T,N,M> x);
 
 // Clamp value to [0,1] range
 __generic<T : __BuiltinFloatingPointType>
diff --git a/source/slang/hlsl.meta.slang.h b/source/slang/hlsl.meta.slang.h
index 67d8d3cc0..94e42b045 100644
--- a/source/slang/hlsl.meta.slang.h
+++ b/source/slang/hlsl.meta.slang.h
@@ -1232,9 +1232,17 @@ SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> ro
 SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int, let M : int> matrix<T,N,M> round(matrix<T,N,M> x);\n")
 SLANG_RAW("\n")
 SLANG_RAW("// Reciprocal of square root\n")
-SLANG_RAW("__generic<T : __BuiltinFloatingPointType> T rsqrt(T x);\n")
-SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> rsqrt(vector<T,N> x);\n")
-SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int, let M : int> matrix<T,N,M> rsqrt(matrix<T,N,M> x);\n")
+SLANG_RAW("__generic<T : __BuiltinFloatingPointType>\n")
+SLANG_RAW("__target_intrinsic(glsl, \"inversesqrt($0)\")\n")
+SLANG_RAW("T rsqrt(T x);\n")
+SLANG_RAW("\n")
+SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int>\n")
+SLANG_RAW("__target_intrinsic(glsl, \"inversesqrt($0)\")\n")
+SLANG_RAW("vector<T,N> rsqrt(vector<T,N> x);\n")
+SLANG_RAW("\n")
+SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int, let M : int>\n")
+SLANG_RAW("__target_intrinsic(glsl, \"inversesqrt($0)\")\n")
+SLANG_RAW("matrix<T,N,M> rsqrt(matrix<T,N,M> x);\n")
 SLANG_RAW("\n")
 SLANG_RAW("// Clamp value to [0,1] range\n")
 SLANG_RAW("__generic<T : __BuiltinFloatingPointType>\n")
diff --git a/tests/bugs/vk-structured-buffer-load.hlsl b/tests/bugs/vk-structured-buffer-load.hlsl
index e8b1eae86..daedc5b66 100644
--- a/tests/bugs/vk-structured-buffer-load.hlsl
+++ b/tests/bugs/vk-structured-buffer-load.hlsl
@@ -1,4 +1,5 @@
 //TEST:CROSS_COMPILE: -profile lib_6_3 -entry HitMain -stage closesthit -target spirv-assembly
+
 struct ParameterBlockTest
 {
     SamplerState sam;
@@ -20,5 +21,5 @@ void HitMain(inout RayHitInfoPacked RayData, BuiltInTriangleIntersectionAttribut
     uint offs = 0;
     float offsfloat = gParamBlock.sbuf.Load(offs);
     
-    RayData.PackedHitInfoA.y = offsfloat;
+    RayData.PackedHitInfoA.y = rsqrt(offsfloat);
 }
diff --git a/tests/bugs/vk-structured-buffer-load.hlsl.glsl b/tests/bugs/vk-structured-buffer-load.hlsl.glsl
index 28703cac4..8060cc921 100644
--- a/tests/bugs/vk-structured-buffer-load.hlsl.glsl
+++ b/tests/bugs/vk-structured-buffer-load.hlsl.glsl
@@ -1,4 +1,6 @@
 // vk-structured-buffer-load.hlsl.glsl
+//TEST_IGNORE_FILE:
+
 #version 460
 layout(row_major) uniform;
 layout(row_major) buffer;
@@ -29,7 +31,9 @@ void main()
 
     float offsfloat_0 = ((gParamBlock_sbuf_0)._data[(int(uint(0)))]);
 
-    _S2.PackedHitInfoA_0.y = offsfloat_0;
-    
+    float _S4 = inversesqrt(offsfloat_0);
+
+    _S2.PackedHitInfoA_0.y = _S4;
+
     return;
-}
\ No newline at end of file
+}
-- 
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