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, 50 insertions, 0 deletions

diff --git a/source/slang/options.cpp b/source/slang/options.cpp
index 485b7d78b..cfa631340 100644
--- a/source/slang/options.cpp
+++ b/source/slang/options.cpp
@@ -147,6 +147,7 @@ struct OptionsParser
         ProfileVersion      profileVersion = ProfileVersion::Unknown;
         SlangTargetFlags    targetFlags = 0;
         int                 targetID = -1;
+        FloatingPointMode   floatingPointMode = FloatingPointMode::Default;
 
         // State for tracking command-line errors
         bool conflictingProfilesSet = false;
@@ -402,6 +403,11 @@ struct OptionsParser
         rawTarget->profileVersion = profileVersion;
     }
 
+    void setFloatingPointMode(RawTarget* rawTarget, FloatingPointMode mode)
+    {
+        rawTarget->floatingPointMode = mode;
+    }
+
     SlangResult parse(
         int             argc,
         char const* const*  argv)
@@ -660,6 +666,28 @@ struct OptionsParser
                     spSetLineDirectiveMode(compileRequest, mode);
 
                 }
+                else if( argStr == "-fp-mode" || argStr == "-floating-point-mode" )
+                {
+                    String name;
+                    SLANG_RETURN_ON_FAIL(tryReadCommandLineArgument(sink, arg, &argCursor, argEnd, name));
+
+                    FloatingPointMode mode = FloatingPointMode::Default;
+                    if(name == "fast")
+                    {
+                        mode = FloatingPointMode::Fast;
+                    }
+                    else if(name == "precise")
+                    {
+                        mode = FloatingPointMode::Precise;
+                    }
+                    else
+                    {
+                        sink->diagnose(SourceLoc(), Diagnostics::unknownFloatingPointMode, name);
+                        return SLANG_FAIL;
+                    }
+
+                    setFloatingPointMode(getCurrentTarget(), mode);
+                }
                 else if (argStr == "--")
                 {
                     // The `--` option causes us to stop trying to parse options,
@@ -983,6 +1011,11 @@ struct OptionsParser
             }
 
             getCurrentTarget()->targetFlags |= defaultTarget.targetFlags;
+
+            if( defaultTarget.floatingPointMode != FloatingPointMode::Default )
+            {
+                setFloatingPointMode(getCurrentTarget(), defaultTarget.floatingPointMode);
+            }
         }
         else
         {
@@ -1018,6 +1051,18 @@ struct OptionsParser
                 }
             }
 
+            if( defaultTarget.floatingPointMode != FloatingPointMode::Default )
+            {
+                if( rawTargets.Count() == 0 )
+                {
+                    sink->diagnose(SourceLoc(), Diagnostics::targetFlagsIgnoredBecauseNoTargets);
+                }
+                else
+                {
+                    sink->diagnose(SourceLoc(), Diagnostics::targetFlagsIgnoredBecauseBeforeAllTargets);
+                }
+            }
+
         }
 
         for(auto& rawTarget : rawTargets)
@@ -1054,6 +1099,11 @@ struct OptionsParser
             {
                 spSetTargetFlags(compileRequest, targetID, rawTarget.targetFlags);
             }
+
+            if( rawTarget.floatingPointMode != FloatingPointMode::Default )
+            {
+                spSetTargetFloatingPointMode(compileRequest, targetID, SlangFloatingPointMode(rawTarget.floatingPointMode));
+            }
         }
 
         if(defaultMatrixLayoutMode != SLANG_MATRIX_LAYOUT_MODE_UNKNOWN)