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

[Vladislav Khmelevsky via llvm-commits]

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

>From 2a184fa60d52c4eb094d2c61e59b7c544afa22c5 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 | 9 +++++----
 2 files changed, 7 insertions(+), 5 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..7d8c7c8772303 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
@@ -9,15 +9,16 @@
 _start:
   // Force BOLT into relocation mode
   .reloc 0, R_RISCV_NONE
-  // BOLT removes this nop so the label difference is initially 8 but should be
-  // 4 after BOLT processes it.
+  // BOLT removes this nop so the label difference is initially 12 but should be
+  // 8 after BOLT processes it.
   nop
   beq x0, x0, _test_end
+  addi x1, x1, 1
 _test_end:
   ret
   .size _start, .-_start
 
   .data
 // CHECK: Hex dump of section '.data':
-// CHECK: 0x{{.*}} 04000000
+// CHECK: 0x{{.*}} 08000000
   .word _test_end - _start