Merge pull request shader-slang#1371 from csyonghe/loop_attrib

Emit [loop] attribute to output HLSL.

Author: csyonghe

source/slang/slang-emit-hlsl.cpp

@@ -673,9 +673,16 @@ void HLSLSourceEmitter::emitVectorTypeNameImpl(IRType* elementType, IRIntegerVal
 
 void HLSLSourceEmitter::emitLoopControlDecorationImpl(IRLoopControlDecoration* decl)
 {
-    if (decl->getMode() == kIRLoopControl_Unroll)
+    switch (decl->getMode())
     {
+    case kIRLoopControl_Unroll:
         m_writer->emit("[unroll]\n");
+        break;
+    case kIRLoopControl_Loop:
+        m_writer->emit("[loop]\n");
+        break;
+    default:
+        break;
     }
 }
 

source/slang/slang-ir-insts.h

@@ -42,6 +42,7 @@ struct IRHighLevelDeclDecoration : IRDecoration
 enum IRLoopControl
 {
     kIRLoopControl_Unroll,
+    kIRLoopControl_Loop,
 };
 
 struct IRLoopControlDecoration : IRDecoration

source/slang/slang-lower-to-ir.cpp

@@ -3353,6 +3353,10 @@ struct StmtLoweringVisitor : StmtVisitor<StmtLoweringVisitor>
         {
             getBuilder()->addLoopControlDecoration(inst, kIRLoopControl_Unroll);
         }
+        else if( stmt->findModifier<LoopAttribute>() )
+        {
+            getBuilder()->addLoopControlDecoration(inst, kIRLoopControl_Loop);
+        }
         // TODO: handle other cases here
     }
 

tests/cross-compile/loop-attribs.slang

@@ -0,0 +1,19 @@
+// loop-attribs.slang
+// Test that loop attributes are correctly emitted to the resulting HLSL.
+
+//TEST:CROSS_COMPILE:-target dxil-assembly  -entry main -stage fragment -profile sm_6_0 
+
+float4 main() : SV_Target
+{
+    float sum = 0.0f;
+    
+    [loop]
+    for (int i = 0; i < 100; i++)
+        sum += float(i);
+
+    [unroll(10)]
+    for (int j = 0; j < 100; j++)
+        sum += float(j);
+
+    return float4(sum, 0, 0, 0);
+}

tests/cross-compile/loop-attribs.slang.hlsl

@@ -0,0 +1,55 @@
+#pragma pack_matrix(column_major)
+
+#line 6 "tests/cross-compile/loop-attribs.slang"
+vector<float,4> main() : SV_TARGET
+{
+    int i_0;
+    float sum_0;
+    int j_0;
+    float sum_1;
+    i_0 = int(0);
+    sum_0 = 0.00000000000000000000;
+    [loop]
+    for(;;)
+    {
+
+#line 11
+        if(i_0 < int(100))
+        {
+        }
+        else
+        {
+            break;
+        }
+        float _S1 = sum_0 + (float) i_0;
+
+#line 11
+        int _S2 = i_0 + (int) int(1);
+        i_0 = _S2;
+        sum_0 = _S1;
+    }
+    j_0 = int(0);
+    sum_1 = sum_0;
+    [unroll]
+    for(;;)
+    {
+
+#line 15
+        if(j_0 < int(100))
+        {
+        }
+        else
+        {
+            break;
+        }
+        float _S3 = sum_1 + (float) j_0;
+
+#line 15
+        int _S4 = j_0 + (int) int(1);
+        j_0 = _S4;
+        sum_1 = _S3;
+    }
+
+#line 18
+    return vector<float,4>(sum_1, (float) int(0), (float) int(0), (float) int(0));
+}