[llvm] [BOLT][NFC] Don't remove nops in non-simple functions (PR #101964)

Vladislav Khmelevsky via llvm-commits llvm-commits at lists.llvm.org
Tue Aug 6 08:43:47 PDT 2024


https://github.com/yota9 updated https://github.com/llvm/llvm-project/pull/101964

>From bd7a82198a55771c8a3403023a3b4675181eb45e Mon Sep 17 00:00:00 2001
From: Vladislav Khmelevsky <och95 at yandex.ru>
Date: Mon, 5 Aug 2024 15:57:06 +0400
Subject: [PATCH] [BOLT][NFC] Don't remove nops in non-simple functions

Follow the logic of https://reviews.llvm.org/D143887 patch (fixed later
by #71377) we don't want to remove nops in non-simple function just in
case there is undetected jump table to minimize chances to break offsets
in it.
---
 bolt/lib/Passes/BinaryPasses.cpp   | 3 ++-
 bolt/test/RISCV/reloc-label-diff.s | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/bolt/lib/Passes/BinaryPasses.cpp b/bolt/lib/Passes/BinaryPasses.cpp
index fa95ad7324ac1..8401658336daa 100644
--- a/bolt/lib/Passes/BinaryPasses.cpp
+++ b/bolt/lib/Passes/BinaryPasses.cpp
@@ -15,6 +15,7 @@
 #include "bolt/Core/ParallelUtilities.h"
 #include "bolt/Passes/ReorderAlgorithm.h"
 #include "bolt/Passes/ReorderFunctions.h"
+#include "bolt/Utils/CommandLineOpts.h"
 #include "llvm/Support/CommandLine.h"
 #include <atomic>
 #include <mutex>
@@ -1923,7 +1924,7 @@ Error RemoveNops::runOnFunctions(BinaryContext &BC) {
   };
 
   ParallelUtilities::PredicateTy SkipFunc = [&](const BinaryFunction &BF) {
-    return BF.shouldPreserveNops();
+    return BF.shouldPreserveNops() || (!opts::StrictMode && !BF.isSimple());
   };
 
   ParallelUtilities::runOnEachFunction(
diff --git a/bolt/test/RISCV/reloc-label-diff.s b/bolt/test/RISCV/reloc-label-diff.s
index 9ad38f86ff541..4649017e4ada7 100644
--- a/bolt/test/RISCV/reloc-label-diff.s
+++ b/bolt/test/RISCV/reloc-label-diff.s
@@ -1,5 +1,5 @@
 // RUN: %clang %cflags -o %t %s
-// RUN: llvm-bolt -o %t.bolt %t
+// RUN: llvm-bolt --strict -o %t.bolt %t
 // RUN: llvm-readelf -x .data %t.bolt | FileCheck %s
 
   .text



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