From ae1be1247896d36fa5dde683b936a28fcfe16614 Mon Sep 17 00:00:00 2001
From: Andy Ayers <andya@microsoft.com>
Date: Sat, 6 May 2023 07:53:10 -0700
Subject: [PATCH] JIT: produce consistent flow graph when producing or
 consuming profile data (#85860)

Always try and merge "branch to next" blocks when building the intial flow graph
if BBINSTR or BBOPT is set.

Fixes #85856.
---
 src/coreclr/jit/compiler.h        | 9 +++++++--
 src/coreclr/jit/fgbasic.cpp       | 7 ++++---
 src/coreclr/jit/fgprofile.cpp     | 4 ++--
 src/coreclr/jit/importer.cpp      | 2 +-
 src/coreclr/jit/importercalls.cpp | 4 ++--
 5 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/src/coreclr/jit/compiler.h b/src/coreclr/jit/compiler.h
index d2c8ebeb72b..fe49473e7c7 100644
--- a/src/coreclr/jit/compiler.h
+++ b/src/coreclr/jit/compiler.h
@@ -9471,9 +9471,14 @@ public:
             return jitFlags->IsSet(JitFlags::JIT_FLAG_BBINSTR);
         }
 
-        bool IsInstrumentedOptimized() const
+        bool IsInstrumentedAndOptimized() const
         {
-            return IsInstrumented() && jitFlags->IsSet(JitFlags::JIT_FLAG_TIER1);
+            return IsInstrumented() && jitFlags->IsSet(JitFlags::JIT_FLAG_BBOPT);
+        }
+
+        bool IsInstrumentedOrOptimized() const
+        {
+            return IsInstrumented() || jitFlags->IsSet(JitFlags::JIT_FLAG_BBOPT);
         }
 
         // true if we should use the PINVOKE_{BEGIN,END} helpers instead of generating
diff --git a/src/coreclr/jit/fgbasic.cpp b/src/coreclr/jit/fgbasic.cpp
index c5d780f7a36..cb627fd3b43 100644
--- a/src/coreclr/jit/fgbasic.cpp
+++ b/src/coreclr/jit/fgbasic.cpp
@@ -1824,8 +1824,9 @@ void Compiler::fgFindJumpTargets(const BYTE* codeAddr, IL_OFFSET codeSize, Fixed
                 // Compute jump target address
                 signed jmpDist = (sz == 1) ? getI1LittleEndian(codeAddr) : getI4LittleEndian(codeAddr);
 
-                if (compIsForInlining() && jmpDist == 0 &&
-                    (opcode == CEE_LEAVE || opcode == CEE_LEAVE_S || opcode == CEE_BR || opcode == CEE_BR_S))
+                if ((jmpDist == 0) &&
+                    (opcode == CEE_LEAVE || opcode == CEE_LEAVE_S || opcode == CEE_BR || opcode == CEE_BR_S) &&
+                    opts.IsInstrumentedOrOptimized())
                 {
                     break; /* NOP */
                 }
@@ -2974,7 +2975,7 @@ unsigned Compiler::fgMakeBasicBlocks(const BYTE* codeAddr, IL_OFFSET codeSize, F
 
                 jmpDist = (sz == 1) ? getI1LittleEndian(codeAddr) : getI4LittleEndian(codeAddr);
 
-                if (compIsForInlining() && jmpDist == 0 && (opcode == CEE_BR || opcode == CEE_BR_S))
+                if ((jmpDist == 0) && (opcode == CEE_BR || opcode == CEE_BR_S) && opts.IsInstrumentedOrOptimized())
                 {
                     continue; /* NOP */
                 }
diff --git a/src/coreclr/jit/fgprofile.cpp b/src/coreclr/jit/fgprofile.cpp
index b391ae99dd4..ef614baca48 100644
--- a/src/coreclr/jit/fgprofile.cpp
+++ b/src/coreclr/jit/fgprofile.cpp
@@ -436,7 +436,7 @@ void BlockCountInstrumentor::RelocateProbes()
 {
     // We only see such blocks when optimizing. They are flagged by the importer.
     //
-    if (!m_comp->opts.IsInstrumentedOptimized() || ((m_comp->optMethodFlags & OMF_HAS_TAILCALL_SUCCESSOR) == 0))
+    if (!m_comp->opts.IsInstrumentedAndOptimized() || ((m_comp->optMethodFlags & OMF_HAS_TAILCALL_SUCCESSOR) == 0))
     {
         // No problematic blocks to worry about.
         //
@@ -1616,7 +1616,7 @@ void EfficientEdgeCountInstrumentor::RelocateProbes()
 {
     // We only see such blocks when optimizing. They are flagged by the importer.
     //
-    if (!m_comp->opts.IsInstrumentedOptimized() || ((m_comp->optMethodFlags & OMF_HAS_TAILCALL_SUCCESSOR) == 0))
+    if (!m_comp->opts.IsInstrumentedAndOptimized() || ((m_comp->optMethodFlags & OMF_HAS_TAILCALL_SUCCESSOR) == 0))
     {
         // No problematic blocks to worry about.
         //
diff --git a/src/coreclr/jit/importer.cpp b/src/coreclr/jit/importer.cpp
index e212041d1bb..e4238fcf719 100644
--- a/src/coreclr/jit/importer.cpp
+++ b/src/coreclr/jit/importer.cpp
@@ -7476,7 +7476,7 @@ void Compiler::impImportBlockCode(BasicBlock* block)
             case CEE_BR_S:
                 jmpDist = (sz == 1) ? getI1LittleEndian(codeAddr) : getI4LittleEndian(codeAddr);
 
-                if (compIsForInlining() && jmpDist == 0)
+                if ((jmpDist == 0) && opts.IsInstrumentedOrOptimized())
                 {
                     break; /* NOP */
                 }
diff --git a/src/coreclr/jit/importercalls.cpp b/src/coreclr/jit/importercalls.cpp
index 993b2843684..ce7d2f286db 100644
--- a/src/coreclr/jit/importercalls.cpp
+++ b/src/coreclr/jit/importercalls.cpp
@@ -1282,7 +1282,7 @@ DONE:
         //    have to check for anything that might introduce a recursive tail call.
         // * We only instrument root method blocks in OSR methods,
         //
-        if ((opts.IsInstrumentedOptimized() || opts.IsOSR()) && !compIsForInlining())
+        if ((opts.IsInstrumentedAndOptimized() || opts.IsOSR()) && !compIsForInlining())
         {
             // If a root method tail call candidate block is not a BBJ_RETURN, it should have a unique
             // BBJ_RETURN successor. Mark that successor so we can handle it specially during profile
@@ -7201,7 +7201,7 @@ bool Compiler::impConsiderCallProbe(GenTreeCall* call, IL_OFFSET ilOffset)
         return false;
     }
 
-    assert(opts.OptimizationDisabled() || opts.IsInstrumentedOptimized());
+    assert(opts.OptimizationDisabled() || opts.IsInstrumentedAndOptimized());
     assert(!compIsForInlining());
 
     // During importation, optionally flag this block as one that