[llvm] [BOLT] Add --pad-funcs-before=func:n (PR #117924)

[Maksim Panchenko via llvm-commits]

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@@ -319,6 +324,32 @@ bool BinaryEmitter::emitFunction(BinaryFunction &Function,
     Streamer.emitCodeAlignment(Function.getAlign(), &*BC.STI);
   }
 
+  if (size_t Padding =
+          opts::padFunction(opts::FunctionPadBeforeSpec, Function)) {
+    // Handle padFuncsBefore after the above alignment logic but before
+    // symbol addresses are decided.
+    if (!BC.HasRelocations) {
+      errs() << "BOLT-ERROR: -pad-before-funcs is not supported in "
+             << "non-relocation mode\n";
+      exit(1);
+    }
+
+    // Preserve Function.getMinAlign().
+    if (!isAligned(Function.getMinAlign(), Padding)) {
+      errs() << "BOLT-ERROR: user-requested " << Padding
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maksfb wrote:

ditto

https://github.com/llvm/llvm-project/pull/117924