[llvm] [NFC][DirectX] Infrastructure to collect shader flags for each function (PR #112967)

[Damyan Pepper via llvm-commits]

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@@ -20,29 +20,37 @@
 using namespace llvm;
 using namespace llvm::dxil;
 
-static void updateFlags(ComputedShaderFlags &Flags, const Instruction &I) {
+static void updateFlags(DXILModuleShaderFlagsInfo &MSFI, const Instruction &I) {
+  ComputedShaderFlags &FSF = MSFI.FuncShaderFlagsMap[I.getFunction()];
   Type *Ty = I.getType();
   if (Ty->isDoubleTy()) {
-    Flags.Doubles = true;
+    FSF.Doubles = true;
     switch (I.getOpcode()) {
     case Instruction::FDiv:
     case Instruction::UIToFP:
     case Instruction::SIToFP:
     case Instruction::FPToUI:
     case Instruction::FPToSI:
-      Flags.DX11_1_DoubleExtensions = true;
+      FSF.DX11_1_DoubleExtensions = true;
       break;
     }
   }
 }
 
-ComputedShaderFlags ComputedShaderFlags::computeFlags(Module &M) {
-  ComputedShaderFlags Flags;
-  for (const auto &F : M)
+static DXILModuleShaderFlagsInfo computeFlags(Module &M) {
+  DXILModuleShaderFlagsInfo MSFI;
+  for (const auto &F : M) {
+    if (F.isDeclaration())
+      continue;
+    if (!MSFI.FuncShaderFlagsMap.contains(&F)) {
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damyanp wrote:

Can F appear multiple times in M?  Or in multiple modules?  I'm wondering why this is needed here.

Do we have test coverage for this case?

https://github.com/llvm/llvm-project/pull/112967