[DirectX] Fix shader flag version-checking logic to match DXC (#136787)

This PR primarily fixes the version-checking logic of the shader flags
`ResMayNotAlias` and `Max64UAVs` to correctly match DXC's behavior.

Primary changes:

- The logic for determining the presence of UAVs for the
`ResMayNotAlias` shader flag checked against the DXIL Version when it
should have been checking against the DXIL Validator Version. (See DXC:
[DxilShaderFlags.cpp#L484](https://github.com/microsoft/DirectXShaderCompiler/blob/f19b5da54170210e3cbc7f080be3f080abc52505/lib/DXIL/DxilShaderFlags.cpp#L484))

- The logic for counting UAVs for the `Max64UAVs` shader flag checked
against the DXIL Version when it should have been checking against the
DXIL Validator Version. (See DXC:
[DxilModule.cpp#L327](https://github.com/microsoft/DirectXShaderCompiler/blob/f19b5da54170210e3cbc7f080be3f080abc52505/lib/DXIL/DxilModule.cpp#L327))

- Tests have been modified to test the corrected behaviors for these two
flags

Additional changes included for consistency:

- The logic for setting `UseNativeLowPrecision` now checks against
Shader Model version instead of DXIL version to be consistent with the
code comments from DXC
([DxilShaderFlags.h#L280](https://github.com/microsoft/DirectXShaderCompiler/blob/f19b5da54170210e3cbc7f080be3f080abc52505/include/dxc/DXIL/DxilShaderFlags.h#L280)).

- An additional test has been added to ensure that the module flag
"dx.nativelowprec" set to 0 does not apply the `UseNativeLowPrecision`
shader flag

- Related shader flag tests were renamed to be more consistent, and some
comments were edited for clarification

- Add obj2yaml tests for the `Max64UAVs` shader flag

Author: Icohedron

llvm/lib/Target/DirectX/DXILShaderFlags.cpp

@@ -132,9 +132,10 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
     case Intrinsic::dx_resource_handlefrombinding: {
       dxil::ResourceTypeInfo &RTI = DRTM[cast<TargetExtType>(II->getType())];
 
-      // Set ResMayNotAlias if DXIL version >= 1.8 and function uses UAVs
+      // Set ResMayNotAlias if DXIL validator version >= 1.8 and the function
+      // uses UAVs
       if (!CSF.ResMayNotAlias && CanSetResMayNotAlias &&
-          MMDI.DXILVersion >= VersionTuple(1, 8) && RTI.isUAV())
+          MMDI.ValidatorVersion >= VersionTuple(1, 8) && RTI.isUAV())
         CSF.ResMayNotAlias = true;
 
       switch (RTI.getResourceKind()) {
@@ -208,15 +209,15 @@ void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
         continue;
       }
 
-      // Set ResMayNotAlias to true if DXIL version < 1.8 and there are UAVs
-      // present globally.
-      if (CanSetResMayNotAlias && MMDI.DXILVersion < VersionTuple(1, 8))
+      // Set ResMayNotAlias to true if DXIL validator version < 1.8 and there
+      // are UAVs present globally.
+      if (CanSetResMayNotAlias && MMDI.ValidatorVersion < VersionTuple(1, 8))
         SCCSF.ResMayNotAlias = !DRM.uavs().empty();
 
       // Set UseNativeLowPrecision using dx.nativelowprec module metadata
       if (auto *NativeLowPrec = mdconst::extract_or_null<ConstantInt>(
               M.getModuleFlag("dx.nativelowprec")))
-        if (MMDI.DXILVersion >= VersionTuple(1, 2) &&
+        if (MMDI.ShaderModelVersion >= VersionTuple(6, 2) &&
             NativeLowPrec->getValue() != 0)
           SCCSF.UseNativeLowPrecision = true;
 
@@ -259,9 +260,9 @@ void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
   // Set the Max64UAVs flag if the number of UAVs is > 8
   uint32_t NumUAVs = 0;
   for (auto &UAV : DRM.uavs())
-    if (MMDI.DXILVersion < VersionTuple(1, 6))
+    if (MMDI.ValidatorVersion < VersionTuple(1, 6))
       NumUAVs++;
-    else // MMDI.DXILVersion >= VersionTuple(1, 6)
+    else // MMDI.ValidatorVersion >= VersionTuple(1, 6)
       NumUAVs += UAV.getBinding().Size;
   if (NumUAVs > 8)
     CombinedSFMask.Max64UAVs = true;

llvm/test/CodeGen/DirectX/ShaderFlags/max-64-uavs-array-sm6_5.ll renamed to llvm/test/CodeGen/DirectX/ShaderFlags/max-64-uavs-array-valver1.5.ll

@@ -1,13 +1,10 @@
 ; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
 
 ; This test makes sure that resource arrays only add 1 to the count of the
-; number of UAVs for setting the shader flag '64 UAV slots' when the shader
-; model version is < 6.6
+; number of UAVs for setting the shader flag '64 UAV slots' when the validator
+; version is < 1.6
 
-; Note: there is no feature flag here (only a module flag), so we don't have an
-; object test.
-
-target triple = "dxil-pc-shadermodel6.5-library"
+target triple = "dxil-pc-shadermodel6.7-library"
 
 ; CHECK:      Combined Shader Flags for Module
 ; CHECK-NEXT: Shader Flags Value: 0x00000000
@@ -29,5 +26,10 @@ define void @test() "hlsl.export" {
   ret void
 }
 
+; Set validator version to 1.5
+!dx.valver = !{!1}
+!1 = !{i32 1, i32 5}
+
+; Set this flag to 1 to prevent the ResMayNotAlias flag from being set
 !llvm.module.flags = !{!0}
 !0 = !{i32 1, !"dx.resmayalias", i32 1}

llvm/test/CodeGen/DirectX/ShaderFlags/max-64-uavs-array-sm6_6.ll renamed to llvm/test/CodeGen/DirectX/ShaderFlags/max-64-uavs-array-valver1.6.ll

@@ -1,13 +1,11 @@
 ; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+; RUN: llc %s --filetype=obj -o - | obj2yaml | FileCheck %s --check-prefix=DXC
 
 ; This test makes sure that resource arrays sizes are accounted for when
 ; counting the number of UAVs for setting the shader flag '64 UAV slots' when
-; the shader model version is >= 6.6
+; the validator version is >= 1.6
 
-; Note: there is no feature flag here (only a module flag), so we don't have an
-; object test.
-
-target triple = "dxil-pc-shadermodel6.6-library"
+target triple = "dxil-pc-shadermodel6.7-library"
 
 ; CHECK:      Combined Shader Flags for Module
 ; CHECK-NEXT: Shader Flags Value: 0x00008000
@@ -29,5 +27,19 @@ define void @test() "hlsl.export" {
   ret void
 }
 
+; Set validator version to 1.6
+!dx.valver = !{!1}
+!1 = !{i32 1, i32 6}
+
+; Set this flag to 1 to prevent the ResMayNotAlias flag from being set
 !llvm.module.flags = !{!0}
 !0 = !{i32 1, !"dx.resmayalias", i32 1}
+
+; DXC: - Name:            SFI0
+; DXC-NEXT:     Size:            8
+; DXC-NEXT:     Flags:
+; DXC-NOT:   {{[A-Za-z]+: +true}}
+; DXC:              Max64UAVs:         true
+; DXC-NOT:   {{[A-Za-z]+: +true}}
+; DXC:       NextUnusedBit:   false
+; DXC: ...

llvm/test/CodeGen/DirectX/ShaderFlags/max-64-uavs.ll

@@ -1,11 +1,9 @@
 ; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+; RUN: llc %s --filetype=obj -o - | obj2yaml | FileCheck %s --check-prefix=DXC
 
 ; This test makes sure that the shader flag '64 UAV slots' is set when there are
 ; more than 8 UAVs in the module.
 
-; Note: there is no feature flag here (only a module flag), so we don't have an
-; object test.
-
 target triple = "dxil-pc-shadermodel6.7-library"
 
 ; CHECK:      Combined Shader Flags for Module
@@ -58,3 +56,12 @@ define void @test() "hlsl.export" {
 
 !llvm.module.flags = !{!0}
 !0 = !{i32 1, !"dx.resmayalias", i32 1}
+
+; DXC: - Name:            SFI0
+; DXC-NEXT:     Size:            8
+; DXC-NEXT:     Flags:
+; DXC-NOT:   {{[A-Za-z]+: +true}}
+; DXC:              Max64UAVs:         true
+; DXC-NOT:   {{[A-Za-z]+: +true}}
+; DXC:       NextUnusedBit:   false
+; DXC: ...

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll

@@ -35,9 +35,11 @@ define float @loadSRV() #0 {
 }
 
 !llvm.module.flags = !{!0}
+!dx.valver = !{!1}
 
 ; dx.resmayalias should never appear with a value of 0.
 ; But if it does, ensure that it has no effect.
 !0 = !{i32 1, !"dx.resmayalias", i32 0}
+!1 = !{i32 1, i32 8}
 
 attributes #0 = { convergent norecurse nounwind "hlsl.export"}

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.6.ll renamed to llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-sm6.6.ll

@@ -1,7 +1,7 @@
 ; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
 
 ; This test checks to ensure the behavior of the DXIL shader flag analysis
-; for the flag ResMayNotAlias is correct when the DXIL Version is 1.6. The
+; for the flag ResMayNotAlias is correct when the DXIL Version is < 1.7. The
 ; ResMayNotAlias flag (0x20000000) should not be set at all.
 
 target triple = "dxil-pc-shadermodel6.6-library"

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll renamed to llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-sm6.7.ll

@@ -1,7 +1,7 @@
 ; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
 
 ; This test checks to ensure the behavior of the DXIL shader flag analysis
-; for the flag ResMayNotAlias is correct when the DXIL Version is 1.7. The
+; for the flag ResMayNotAlias is correct when the DXIL Version is >= 1.7. The
 ; ResMayNotAlias flag (0x20000000) should be set on all functions if there are
 ; one or more UAVs present globally in the module.
 

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll renamed to llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-valver1.8.ll

@@ -1,11 +1,11 @@
 ; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
 
-; This test checks to ensure the behavior of the DXIL shader flag analysis
-; for the flag ResMayNotAlias is correct when the DXIL Version is 1.8. The
-; ResMayNotAlias flag (0x20000000) should only be set when a function uses a
+; This test checks to ensure the behavior of the DXIL shader flag analysis for
+; the flag ResMayNotAlias is correct when the DXIL validator version is >= 1.8.
+; The ResMayNotAlias flag (0x20000000) should only be set when a function uses a
 ; UAV.
 
-target triple = "dxil-pc-shadermodel6.8-library"
+target triple = "dxil-pc-shadermodel6.7-library"
 
 ; CHECK:      Combined Shader Flags for Module
 ; CHECK-NEXT: Shader Flags Value: 0x200000010
@@ -35,4 +35,7 @@ define float @loadSRV() #0 {
   ret float %val
 }
 
+!dx.valver = !{!1}
+!1 = !{i32 1, i32 8}
+
 attributes #0 = { convergent norecurse nounwind "hlsl.export"}

llvm/test/CodeGen/DirectX/ShaderFlags/use-native-low-precision-0.ll

@@ -0,0 +1,37 @@
+; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+
+; Check that when the dx.nativelowprec module flag is set to 0, the module-level
+; shader flag UseNativeLowPrecision is not set
+
+target triple = "dxil-pc-shadermodel6.7-library"
+
+;CHECK: ; Combined Shader Flags for Module
+;CHECK-NEXT: ; Shader Flags Value: 0x00000020
+;CHECK-NEXT: ;
+;CHECK-NEXT: ; Note: shader requires additional functionality:
+;CHECK-NEXT: ; Note: extra DXIL module flags:
+;CHECK-NEXT: ;       D3D11_1_SB_GLOBAL_FLAG_ENABLE_MINIMUM_PRECISION
+;CHECK-NOT:  ;       Native 16bit types enabled
+;CHECK-NEXT: ;
+;CHECK-NEXT: ; Shader Flags for Module Functions
+
+;CHECK-LABEL: ; Function add_i16 : 0x00000020
+define i16 @add_i16(i16 %a, i16 %b) {
+  %sum = add i16 %a, %b
+  ret i16 %sum
+}
+
+;CHECK-LABEL: ; Function add_i32 : 0x00000000
+define i32 @add_i32(i32 %a, i32 %b) {
+  %sum = add i32 %a, %b
+  ret i32 %sum
+}
+
+;CHECK-LABEL: ; Function add_half : 0x00000020
+define half @add_half(half %a, half %b) {
+  %sum = fadd half %a, %b
+  ret half %sum
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"dx.nativelowprec", i32 0}