JIT: add ability to order blocks in dump by bbNum or bbID (#70399)

By default the JIT will dump blocks in bbNext order. This adds
other ordering options, specified by `JitDumpFgBlockOrder`:
* `0 (default) bbNext`
* `1 bbNum`
* `2 bbID`

`bbID` in particular is useful when comparing JIT dumps where blocks
have been reordered but the blocks themselves have similar content.

Author: AndyAyersMS

src/coreclr/jit/compiler.h

@@ -4247,7 +4247,8 @@ class Compiler
     unsigned        fgEdgeCount;    // # of control flow edges between the BBs
     unsigned        fgBBcount;      // # of BBs in the method
 #ifdef DEBUG
-    unsigned fgBBcountAtCodegen; // # of BBs in the method at the start of codegen
+    unsigned                     fgBBcountAtCodegen; // # of BBs in the method at the start of codegen
+    jitstd::vector<BasicBlock*>* fgBBOrder;          // ordered vector of BBs
 #endif
     unsigned     fgBBNumMax;       // The max bbNum that has been assigned to basic blocks
     unsigned     fgDomBBcount;     // # of BBs for which we have dominator and reachability information

src/coreclr/jit/fgbasic.cpp

@@ -61,6 +61,7 @@ void Compiler::fgInit()
 
 #ifdef DEBUG
     fgBBcountAtCodegen = 0;
+    fgBBOrder          = nullptr;
 #endif // DEBUG
 
     fgBBNumMax        = 0;

src/coreclr/jit/fgdiagnostic.cpp

@@ -8,6 +8,7 @@
 #endif
 
 #include "allocacheck.h" // for alloca
+#include "jitstd/algorithm.h"
 
 // Flowgraph Check and Dump Support
 
@@ -2181,25 +2182,67 @@ void Compiler::fgTableDispBasicBlock(BasicBlock* block, int ibcColWidth /* = 0 *
 
 void Compiler::fgDispBasicBlocks(BasicBlock* firstBlock, BasicBlock* lastBlock, bool dumpTrees)
 {
-    BasicBlock* block;
+    // Build vector of blocks in order.
+    //
+    if (fgBBOrder == nullptr)
+    {
+        CompAllocator allocator = getAllocator(CMK_DebugOnly);
+        fgBBOrder               = new (allocator) jitstd::vector<BasicBlock*>(allocator);
+    }
+
+    fgBBOrder->reserve(fgBBcount);
+    fgBBOrder->clear();
 
-    // If any block has IBC data, we add an "IBC weight" column just before the 'IL range' column. This column is as
-    // wide as necessary to accommodate all the various IBC weights. It's at least 4 characters wide, to accommodate
-    // the "IBC" title and leading space.
     int ibcColWidth = 0;
-    for (block = firstBlock; block != nullptr; block = block->bbNext)
+
+    for (BasicBlock* block = firstBlock; block != nullptr; block = block->bbNext)
     {
         if (block->hasProfileWeight())
         {
             int thisIbcWidth = CountDigits(block->bbWeight);
             ibcColWidth      = max(ibcColWidth, thisIbcWidth);
         }
 
+        fgBBOrder->push_back(block);
+
         if (block == lastBlock)
         {
             break;
         }
     }
+
+    bool inDefaultOrder = true;
+
+    struct fgBBNumCmp
+    {
+        bool operator()(const BasicBlock* bb1, const BasicBlock* bb2)
+        {
+            return bb1->bbNum < bb2->bbNum;
+        }
+    };
+
+    struct fgBBIDCmp
+    {
+        bool operator()(const BasicBlock* bb1, const BasicBlock* bb2)
+        {
+            return bb1->bbID < bb2->bbID;
+        }
+    };
+
+    // Optionally sort
+    //
+    if (JitConfig.JitDumpFgBlockOrder() == 1)
+    {
+        jitstd::sort(fgBBOrder->begin(), fgBBOrder->end(), fgBBNumCmp());
+        inDefaultOrder = false;
+    }
+    else if (JitConfig.JitDumpFgBlockOrder() == 2)
+    {
+
+        jitstd::sort(fgBBOrder->begin(), fgBBOrder->end(), fgBBIDCmp());
+        inDefaultOrder = false;
+    }
+
     if (ibcColWidth > 0)
     {
         ibcColWidth = max(ibcColWidth, 3) + 1; // + 1 for the leading space
@@ -2234,7 +2277,7 @@ void Compiler::fgDispBasicBlocks(BasicBlock* firstBlock, BasicBlock* lastBlock,
 
     // clang-format on
 
-    for (block = firstBlock; block; block = block->bbNext)
+    for (BasicBlock* block : *fgBBOrder)
     {
         // First, do some checking on the bbPrev links
         if (block->bbPrev)
@@ -2249,7 +2292,7 @@ void Compiler::fgDispBasicBlocks(BasicBlock* firstBlock, BasicBlock* lastBlock,
             printf("bad prev link!\n");
         }
 
-        if (block == fgFirstColdBlock)
+        if (inDefaultOrder && (block == fgFirstColdBlock))
         {
             printf(
                 "~~~~~~%*s~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~%*s~~~~~~~~~~~~~~~~~~~~~~~~~~%*s~~~~~~~~~~~~~~~~~~~~~~~~"
@@ -2258,7 +2301,7 @@ void Compiler::fgDispBasicBlocks(BasicBlock* firstBlock, BasicBlock* lastBlock,
         }
 
 #if defined(FEATURE_EH_FUNCLETS)
-        if (block == fgFirstFuncletBB)
+        if (inDefaultOrder && (block == fgFirstFuncletBB))
         {
             printf(
                 "++++++%*s+++++++++++++++++++++++++++++++++++++%*s++++++++++++++++++++++++++%*s++++++++++++++++++++++++"
@@ -2282,7 +2325,13 @@ void Compiler::fgDispBasicBlocks(BasicBlock* firstBlock, BasicBlock* lastBlock,
 
     if (dumpTrees)
     {
-        fgDumpTrees(firstBlock, lastBlock);
+        for (BasicBlock* block : *fgBBOrder)
+        {
+            fgDumpBlock(block);
+        }
+        printf("\n-----------------------------------------------------------------------------------------------------"
+               "----"
+               "----------\n");
     }
 }
 

src/coreclr/jit/jitconfigvalues.h

@@ -243,6 +243,8 @@ CONFIG_INTEGER(JitDumpFgBlockID, W("JitDumpFgBlockID"), 0) // 0 == display block
                                                            // bbNum and bbID
 CONFIG_INTEGER(JitDumpFgBlockFlags, W("JitDumpFgBlockFlags"), 0) // 0 == don't display block flags; 1 == display flags
 CONFIG_INTEGER(JitDumpFgLoopFlags, W("JitDumpFgLoopFlags"), 0)   // 0 == don't display loop flags; 1 == display flags
+CONFIG_INTEGER(JitDumpFgBlockOrder, W("JitDumpFgBlockOrder"), 0) // 0 == bbNext order;  1 == bbNum order; 2 == bbID
+                                                                 // order
 
 CONFIG_STRING(JitDumpPreciseDebugInfoFile, W("JitDumpPreciseDebugInfoFile"))
 CONFIG_INTEGER(JitDisasmWithDebugInfo, W("JitDisasmWithDebugInfo"), 0)