llvm-reduce: Clone properties of blocks

getSuccProbability was private for some reason, saying to go through
MachineBranchProbabilityInfo. There doesn't seem to be much point to
that, as that wrapper directly calls this.

Like other areas, some of these fields aren't handled by the MIR
printer/parser so aren't tested.

llvm/include/llvm/CodeGen/MachineBasicBlock.h

@@ -1086,6 +1086,11 @@ class MachineBasicBlock
     IrrLoopHeaderWeight = Weight;
   }
 
+  /// Return probability of the edge from this block to MBB. This method should
+  /// NOT be called directly, but by using getEdgeProbability method from
+  /// MachineBranchProbabilityInfo class.
+  BranchProbability getSuccProbability(const_succ_iterator Succ) const;
+
 private:
   /// Return probability iterator corresponding to the I successor iterator.
   probability_iterator getProbabilityIterator(succ_iterator I);
@@ -1095,11 +1100,6 @@ class MachineBasicBlock
   friend class MachineBranchProbabilityInfo;
   friend class MIPrinter;
 
-  /// Return probability of the edge from this block to MBB. This method should
-  /// NOT be called directly, but by using getEdgeProbability method from
-  /// MachineBranchProbabilityInfo class.
-  BranchProbability getSuccProbability(const_succ_iterator Succ) const;
-
   // Methods used to maintain doubly linked list of blocks...
   friend struct ilist_callback_traits<MachineBasicBlock>;
 

llvm/test/tools/llvm-reduce/mir/preserve-block-info.mir

@@ -0,0 +1,72 @@
+# REQUIRES: amdgpu-registered-target
+# RUN: llvm-reduce -simplify-mir -mtriple=amdgcn-amd-amdhsa --test FileCheck --test-arg --check-prefix=CHECK-INTERESTINGNESS --test-arg %s --test-arg --input-file %s -o %t 2> %t.log
+# RUN: FileCheck --match-full-lines --check-prefix=RESULT %s < %t
+
+# CHECK-INTERESTINGNESS: V_MOV_B32
+
+
+# RESULT: bb.0.entry:
+# RESULT: %{{[0-9]+}}:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
+
+# RESULT: bb.1 (address-taken, align 8):
+# RESULT: bb.2 (landing-pad, align 16):
+# RESULT: bb.3 (inlineasm-br-indirect-target):
+# RESULT: bb.4 (ehfunclet-entry):
+# RESULT: bb.5 (bbsections 1):
+# RESULT: bb.6 (bbsections 2):
+# RESULT: bb.7 (bbsections 3):
+# RESULT: bb.8:
+# RESULT-NEXT: successors: %bb.9(0x66666666), %bb.10(0x1999999a)
+# RESULT: bb.9:
+# RESULT: bb.10.exitblock:
+
+--- |
+  define void @func(i32 %size)  {
+  entry:
+    br label %exitblock
+
+  exitblock:
+    ret void
+  }
+
+...
+
+---
+name: func
+alignment:       32
+exposesReturnsTwice: true
+legalized:       true
+regBankSelected: true
+selected:        true
+failedISel:      true
+tracksRegLiveness: true
+hasWinCFI:       true
+failsVerification: true
+tracksDebugUserValues: true
+body:             |
+  bb.0.entry:
+    S_NOP 0
+    %0:vgpr_32 = V_MOV_B32_e32 0, implicit $exec
+
+  bb.1 (address-taken, align 8):
+
+  bb.2 (landing-pad, align 16):
+
+  bb.3 (inlineasm-br-indirect-target):
+
+  bb.4 (ehfunclet-entry):
+
+  bb.5 (bbsections 1):
+  bb.6 (bbsections 2):
+  bb.7 (bbsections 3):
+
+  bb.8:
+    successors: %bb.9(4), %bb.10(1)
+    S_CBRANCH_SCC1 %bb.10, implicit undef $scc
+    S_BRANCH %bb.9
+
+  bb.9:
+
+  bb.10.exitblock:
+    S_ENDPGM 0, implicit %0
+...

llvm/tools/llvm-reduce/ReducerWorkItem.cpp

@@ -125,8 +125,41 @@ static std::unique_ptr<MachineFunction> cloneMF(MachineFunction *SrcMF) {
   auto *DstMRI = &DstMF->getRegInfo();
 
   // Clone blocks.
-  for (MachineBasicBlock &SrcMBB : *SrcMF)
-    Src2DstMBB[&SrcMBB] = DstMF->CreateMachineBasicBlock();
+  for (MachineBasicBlock &SrcMBB : *SrcMF) {
+    MachineBasicBlock *DstMBB =
+        DstMF->CreateMachineBasicBlock(SrcMBB.getBasicBlock());
+    Src2DstMBB[&SrcMBB] = DstMBB;
+
+    if (SrcMBB.hasAddressTaken())
+      DstMBB->setHasAddressTaken();
+
+    // FIXME: This is not serialized
+    if (SrcMBB.hasLabelMustBeEmitted())
+      DstMBB->setLabelMustBeEmitted();
+
+    DstMBB->setAlignment(SrcMBB.getAlignment());
+
+    // FIXME: This is not serialized
+    DstMBB->setMaxBytesForAlignment(SrcMBB.getMaxBytesForAlignment());
+
+    DstMBB->setIsEHPad(SrcMBB.isEHPad());
+    DstMBB->setIsEHScopeEntry(SrcMBB.isEHScopeEntry());
+    DstMBB->setIsEHCatchretTarget(SrcMBB.isEHCatchretTarget());
+    DstMBB->setIsEHFuncletEntry(SrcMBB.isEHFuncletEntry());
+
+    // FIXME: These are not serialized
+    DstMBB->setIsCleanupFuncletEntry(SrcMBB.isCleanupFuncletEntry());
+    DstMBB->setIsBeginSection(SrcMBB.isBeginSection());
+    DstMBB->setIsEndSection(SrcMBB.isEndSection());
+
+    DstMBB->setSectionID(SrcMBB.getSectionID());
+    DstMBB->setIsInlineAsmBrIndirectTarget(
+        SrcMBB.isInlineAsmBrIndirectTarget());
+
+    // FIXME: This is not serialized
+    if (Optional<uint64_t> Weight = SrcMBB.getIrrLoopHeaderWeight())
+      DstMBB->setIrrLoopHeaderWeight(*Weight);
+  }
 
   const MachineFrameInfo &SrcMFI = SrcMF->getFrameInfo();
   MachineFrameInfo &DstMFI = DstMF->getFrameInfo();
@@ -187,25 +220,36 @@ static std::unique_ptr<MachineFunction> cloneMF(MachineFunction *SrcMF) {
     }
   }
 
+  const TargetSubtargetInfo &STI = DstMF->getSubtarget();
+  const TargetInstrInfo *TII = STI.getInstrInfo();
+  const TargetRegisterInfo *TRI = STI.getRegisterInfo();
+
   // Link blocks.
   for (auto &SrcMBB : *SrcMF) {
     auto *DstMBB = Src2DstMBB[&SrcMBB];
     DstMF->push_back(DstMBB);
+
     for (auto It = SrcMBB.succ_begin(), IterEnd = SrcMBB.succ_end();
          It != IterEnd; ++It) {
       auto *SrcSuccMBB = *It;
       auto *DstSuccMBB = Src2DstMBB[SrcSuccMBB];
-      DstMBB->addSuccessor(DstSuccMBB);
+      DstMBB->addSuccessor(DstSuccMBB, SrcMBB.getSuccProbability(It));
     }
     for (auto &LI : SrcMBB.liveins())
       DstMBB->addLiveIn(LI);
+
+    // Make sure MRI knows about registers clobbered by unwinder.
+    if (DstMBB->isEHPad()) {
+      if (auto *RegMask = TRI->getCustomEHPadPreservedMask(*DstMF))
+        DstMRI->addPhysRegsUsedFromRegMask(RegMask);
+    }
   }
+
   // Clone instructions.
   for (auto &SrcMBB : *SrcMF) {
     auto *DstMBB = Src2DstMBB[&SrcMBB];
     for (auto &SrcMI : SrcMBB) {
-      const auto &MCID =
-          DstMF->getSubtarget().getInstrInfo()->get(SrcMI.getOpcode());
+      const auto &MCID = TII->get(SrcMI.getOpcode());
       auto *DstMI = DstMF->CreateMachineInstr(MCID, SrcMI.getDebugLoc(),
                                               /*NoImplicit=*/true);
       DstMBB->push_back(DstMI);