[XRay][clang] Make -fxray-modes= additive

[dberris]

Summary

This allows us to do the following:

clang -fxray-modes=none ... -fxray-modes=xray-basic

It's important to be able to do this in cases where we'd like to
specialise the configuration for the invocation of the compiler, in
various scripting environments.

This is related to llvm.org/PR37066, a follow-up to D45474.

clang/lib/Driver/XRayArgs.cpp

if (Args.hasFlag(options::OPT_fxray_instrument,
     }
 
     // Get the list of modes we want to support.
     auto SpecifiedModes = Args.getAllArgValues(options::OPT_fxray_modes);
     if (SpecifiedModes.empty())
       llvm::copy(XRaySupportedModes, std::back_inserter(Modes));
     else
       for (const auto &Arg : SpecifiedModes) {
-        if (Arg == "none") {
-          Modes.clear();
-          break;
-        }
-        if (Arg == "all") {
-          Modes.clear();
-          llvm::copy(XRaySupportedModes, std::back_inserter(Modes));
-          break;
-        }
-
         // Parse CSV values for -fxray-modes=...
         llvm::SmallVector<StringRef, 2> ModeParts;
         llvm::SplitString(Arg, ModeParts, ",");
         for (const auto &M : ModeParts)
+          if (M == "none")
+            Modes.clear();
+          else if (M == "all")
+            llvm::copy(XRaySupportedModes, std::back_inserter(Modes));
+          else
             Modes.push_back(M);
       }
 
     // Then we want to sort and unique the modes we've collected.
     std::sort(Modes.begin(), Modes.end());
     Modes.erase(std::unique(Modes.begin(), Modes.end()), Modes.end());
   }
 }
 
for (const auto &AttrFile : AttrListFiles) {
     CmdArgs.push_back(Args.MakeArgString(AttrListFileOpt));
   }
 
   for (const auto &Dep : ExtraDeps) {
     SmallString<64> ExtraDepOpt("-fdepfile-entry=");
     ExtraDepOpt += Dep;
     CmdArgs.push_back(Args.MakeArgString(ExtraDepOpt));
   }
+
+  for (const auto &Mode : Modes) {
+    SmallString<64> ModeOpt("-fxray-modes=");
+    ModeOpt += Mode;
+    CmdArgs.push_back(Args.MakeArgString(ModeOpt));
+  }
 }

clang/test/Driver/XRay/xray-mode-flags.cpp

 // RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=xray-fdr %s -### \
 // RUN:     2>&1 | FileCheck --check-prefix FDR %s
 // RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=xray-basic %s \
 // RUN:     -### 2>&1 | FileCheck --check-prefix BASIC %s
 // RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=all -### %s \
 // RUN:     2>&1 | FileCheck --check-prefixes FDR,BASIC %s
 // RUN: %clang -v -o /dev/null -fxray-instrument \
 // RUN:     -fxray-modes=xray-fdr,xray-basic -### %s 2>&1 | \
 // RUN:     FileCheck --check-prefixes FDR,BASIC %s
 // RUN: %clang -v -o /dev/null -fxray-instrument \
 // RUN:     -fxray-modes=xray-fdr -fxray-modes=xray-basic -### %s 2>&1 | \
 // RUN:     FileCheck --check-prefixes FDR,BASIC %s
 // RUN: %clang -v -o /dev/null -fxray-instrument -### %s \
 // RUN:     2>&1 | FileCheck --check-prefixes FDR,BASIC %s
 // RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=none -### %s \
 // RUN:     2>&1 | FileCheck --check-prefixes NONE %s
+//
+// We also should support overriding the modes in an additive manner.
+//
+// RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=none,xray-fdr \
+// RUN:     -### %s \
+// RUN:     2>&1 | FileCheck --check-prefixes FDR %s
+// RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=xray-fdr,none \
+// RUN:     -### %s \
+// RUN:     2>&1 | FileCheck --check-prefixes NONE %s
+// RUN: %clang -v -o /dev/null -fxray-instrument -fxray-modes=none,all \
+// RUN:     -### %s \
+// RUN:     2>&1 | FileCheck --check-prefixes FDR,BASIC %s
 
 // BASIC: libclang_rt.xray-basic
 // FDR: libclang_rt.xray-fdr
 // NONE-NOT: libclang_rt.xray-basic
 // NONE-NOT: libclang_rt.xray-fdr
 // REQUIRES-ANY: linux, freebsd
 // REQUIRES-ANY: amd64, x86_64, x86_64h, arm, aarch64, arm64