[llvm] [llvm-exegesis] Error instead of aborting on verification failure (PR #137581)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-tools-llvm-exegesis

Author: Aiden Grossman (boomanaiden154)

<details>
<summary>Changes</summary>

This patch makes llvm-exegesis emit an error when the machine function fails in MachineVerification rather than aborting. This allows downstream users (particularly https://github.com/google/gematria) to handle these errors rather than having the entire process crash. This essentially be NFC from the user perspective minus the addition of the new error message.

---
Full diff: https://github.com/llvm/llvm-project/pull/137581.diff


1 Files Affected:

- (modified) llvm/tools/llvm-exegesis/lib/Assembler.cpp (+6-3) 


``````````diff
diff --git a/llvm/tools/llvm-exegesis/lib/Assembler.cpp b/llvm/tools/llvm-exegesis/lib/Assembler.cpp
index f638478e0c51d..67f3d75a5e879 100644
--- a/llvm/tools/llvm-exegesis/lib/Assembler.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Assembler.cpp
@@ -29,6 +29,7 @@
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/Object/SymbolSize.h"
 #include "llvm/Support/Alignment.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 
@@ -323,10 +324,8 @@ Error assembleToStream(const ExegesisTarget &ET,
   TPC->printAndVerify("After ExegesisTarget::addTargetSpecificPasses");
   // Adding the following passes:
   // - postrapseudos: expands pseudo return instructions used on some targets.
-  // - machineverifier: checks that the MachineFunction is well formed.
   // - prologepilog: saves and restore callee saved registers.
-  for (const char *PassName :
-       {"postrapseudos", "machineverifier", "prologepilog"})
+  for (const char *PassName : {"postrapseudos", "prologepilog"})
     if (addPass(PM, PassName, *TPC))
       return make_error<Failure>("Unable to add a mandatory pass");
   TPC->setInitialized();
@@ -337,6 +336,10 @@ Error assembleToStream(const ExegesisTarget &ET,
     return make_error<Failure>("Cannot add AsmPrinter passes");
 
   PM.run(*Module); // Run all the passes
+  bool MFWellFormed =
+      MF.verify(nullptr, "llvm-exegesis Assembly", &outs(), false);
+  if (!MFWellFormed)
+    return make_error<Failure>("The machine function failed verification.");
   return Error::success();
 }
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/137581