Add support for a "strict" floating-point mode (#709)

This change adds an API function and command line options for controlling the default floating-point behavior for a target, with options for "fast" and "precise" computation.
The "precise" option gets mapped to the "IEEE strictness" mode in `fxc` and `dxc` (there is currently no equivalent option for glslang that I could find).

1 files changed, 14 insertions, 2 deletions

diff --git a/source/slang/compiler.cpp b/source/slang/compiler.cpp
index ed222d181..52a31645c 100644
--- a/source/slang/compiler.cpp
+++ b/source/slang/compiler.cpp
@@ -428,6 +428,18 @@ namespace Slang
             dxMacros = dxMacrosStorage.Buffer();
         }
 
+        DWORD flags = 0;
+
+        switch( targetReq->floatingPointMode )
+        {
+        default:
+            break;
+
+        case FloatingPointMode::Precise:
+            flags |= D3DCOMPILE_IEEE_STRICTNESS;
+            break;
+        }
+
         ID3DBlob* codeBlob;
         ID3DBlob* diagnosticsBlob;
         HRESULT hr = D3DCompile_(
@@ -438,8 +450,8 @@ namespace Slang
             nullptr,
             getText(entryPoint->name).begin(),
             GetHLSLProfileName(profile).Buffer(),
-            0,
-            0,
+            flags,
+            0, // unused: effect flags
             &codeBlob,
             &diagnosticsBlob);