[clang][deps] Improve timing output (llvm#113726)

This patch adds the number of executed instructions into the timing
output, which provides more stable results compared to wall or process
time.

The format itself is also tweaked so that it's more amenable for direct
import into a spreadsheet editor.

(cherry picked from commit 39303e2)

Author: jansvoboda11

clang/test/ClangScanDeps/print-timing.c

@@ -3,7 +3,8 @@
 
 // RUN: clang-scan-deps -compilation-database %t/cdb.json -print-timing > %t/result.json 2>%t/errs
 // RUN: cat %t/errs | FileCheck %s
-// CHECK: clang-scan-deps timing: {{[0-9]+}}.{{[0-9][0-9]}}s wall, {{[0-9]+}}.{{[0-9][0-9]}}s process
+// CHECK:      wall time [s]              process time [s]           instruction count
+// CHECK-NEXT: {{[0-9]+}}.{{([0-9]{4})}}  {{[0-9]+}}.{{([0-9]{4})}}  {{[0-9]+}}
 
 //--- cdb.json
 []

clang/tools/clang-scan-deps/ClangScanDeps.cpp

@@ -1398,10 +1398,15 @@ int clang_scan_deps_main(int argc, char **argv, const llvm::ToolContext &) {
   }
 
   T.stopTimer();
-  if (PrintTiming)
-    llvm::errs() << llvm::format(
-        "clang-scan-deps timing: %0.2fs wall, %0.2fs process\n",
-        T.getTotalTime().getWallTime(), T.getTotalTime().getProcessTime());
+  if (PrintTiming) {
+    llvm::errs() << "wall time [s]\t"
+                 << "process time [s]\t"
+                 << "instruction count\n";
+    const llvm::TimeRecord &R = T.getTotalTime();
+    llvm::errs() << llvm::format("%0.4f", R.getWallTime()) << "\t"
+                 << llvm::format("%0.4f", R.getProcessTime()) << "\t"
+                 << llvm::format("%llu", R.getInstructionsExecuted()) << "\n";
+  }
 
   if (RoundTripArgs)
     if (FD && FD->roundTripCommands(llvm::errs()))