[BOLT] Require CFG in BAT mode

[aaupov]

getFallthroughsInTrace requires CFG for functions not covered by BAT,
even in BAT/fdata mode. BAT-covered functions go through special
handling in fdata (BAT->getFallthroughsInTrace) and YAML
(DataAggregator::writeBATYAML) modes.

Since all modes (BAT/no-BAT, YAML/fdata) now need disassembly/CFG
construction:

• drop special BAT/fdata handling that omitted disassembly/CFG in
  RewriteInstance::run, enabling CFG for all non-BAT functions,
• switch getFallthroughsInTrace to check if a function has CFG,
• which allows emitting profile for non-simple functions in all modes.

Previously, traces in non-simple functions were reported as invalid/
mismatching disassembled function contents. This change reduces the
number of such invalid traces and increases the number of profiled
functions. These functions may participate in function reordering via
call graph profile.

Test Plan: updated unclaimed-jt-entries.s

[llvmbot]

@llvm/pr-subscribers-bolt

Author: Amir Ayupov (aaupov)

Changes

getFallthroughsInTrace for non-BAT functions requires CFG even for
fdata output only. Since all modes (BAT/non-BAT, YAML/fdata) need CFG:

• drop special BAT/fdata handling in RewriteInstance::run,
• in getFallthroughsInTrace, directly check if a function has CFG
  constructed => allow non-simple functions.

Test Plan: updated unclaimed-jt-entries.s

---

Full diff: https://github.com/llvm/llvm-project/pull/150488.diff

3 Files Affected:

• (modified) bolt/lib/Profile/DataAggregator.cpp (+2-3)
• (modified) bolt/lib/Rewrite/RewriteInstance.cpp (-15)
• (modified) bolt/test/X86/unclaimed-jt-entries.s (+16-2)

diff --git a/bolt/lib/Profile/DataAggregator.cpp b/bolt/lib/Profile/DataAggregator.cpp
index e236cbab8fc87..f56f5963305c5 100644
--- a/bolt/lib/Profile/DataAggregator.cpp
+++ b/bolt/lib/Profile/DataAggregator.cpp
@@ -906,11 +906,10 @@ DataAggregator::getFallthroughsInTrace(BinaryFunction &BF, const Trace &Trace,
   if (BF.isPseudo())
     return Branches;
 
-  if (!BF.isSimple())
+  // Can only record traces in CFG state
+  if (!BF.hasCFG())
     return std::nullopt;
 
-  assert(BF.hasCFG() && "can only record traces in CFG state");
-
   const BinaryBasicBlock *FromBB = BF.getBasicBlockContainingOffset(From);
   const BinaryBasicBlock *ToBB = BF.getBasicBlockContainingOffset(To);
 
diff --git a/bolt/lib/Rewrite/RewriteInstance.cpp b/bolt/lib/Rewrite/RewriteInstance.cpp
index 7fbc933cade5b..7fac315ca9b27 100644
--- a/bolt/lib/Rewrite/RewriteInstance.cpp
+++ b/bolt/lib/Rewrite/RewriteInstance.cpp
@@ -714,21 +714,6 @@ Error RewriteInstance::run() {
 
   preprocessProfileData();
 
-  // Skip disassembling if we have a translation table and we are running an
-  // aggregation job.
-  if (opts::AggregateOnly && BAT->enabledFor(InputFile)) {
-    // YAML profile in BAT mode requires CFG for .bolt.org.text functions
-    if (!opts::SaveProfile.empty() ||
-        opts::ProfileFormat == opts::ProfileFormatKind::PF_YAML) {
-      selectFunctionsToProcess();
-      disassembleFunctions();
-      processMetadataPreCFG();
-      buildFunctionsCFG();
-    }
-    processProfileData();
-    return Error::success();
-  }
-
   selectFunctionsToProcess();
 
   readDebugInfo();
diff --git a/bolt/test/X86/unclaimed-jt-entries.s b/bolt/test/X86/unclaimed-jt-entries.s
index 1102e4ae413e2..31b72c47125ae 100644
--- a/bolt/test/X86/unclaimed-jt-entries.s
+++ b/bolt/test/X86/unclaimed-jt-entries.s
@@ -18,6 +18,18 @@
 
 # RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %s -o %t.o
 # RUN: %clang %cflags -no-pie %t.o -o %t.exe -Wl,-q
+
+## Check that non-simple function profile is emitted in perf2bolt mode
+# RUN: link_fdata %s %t.exe %t.pa PREAGG
+# RUN: llvm-strip -N L5 -N L5_ret %t.exe
+# RUN: perf2bolt %t.exe -p %t.pa --pa -o %t.fdata -strict=0 -print-profile \
+# RUN:   -print-only=main | FileCheck %s --check-prefix=CHECK-P2B
+# CHECK-P2B: PERF2BOLT: traces mismatching disassembled function contents: 0
+# CHECK-P2B: Binary Function "main"
+# CHECK-P2B: IsSimple : 0
+# RUN: FileCheck %s --input-file %t.fdata --check-prefix=CHECK-FDATA
+# CHECK-FDATA: 1 main 0 1 main 7 0 1
+
 # RUN: llvm-bolt %t.exe -v=1 -o %t.out 2>&1 | FileCheck %s
 
 # CHECK: BOLT-WARNING: unclaimed data to code reference (possibly an unrecognized jump table entry) to .Ltmp[[#]] in main
@@ -33,8 +45,10 @@
   .size main, .Lend-main
 main:
   jmp *L4-24(,%rdi,8)
-.L5:
+# PREAGG: T #main# #L5# #L5_ret# 1
+L5:
   movl $4, %eax
+L5_ret:
   ret
 .L9:
   movl $2, %eax
@@ -58,7 +72,7 @@ L4:
   .quad .L3
   .quad .L6
   .quad .L3
-  .quad .L5
+  .quad L5
   .quad .L3
   .quad .L3
   .quad .L3