From: Quentin Colombet <qcolombet@apple.com>
Date: Tue, 19 Sep 2017 22:03:50 +0000 (+0000)
Subject: Revert "[MIRPrinter] Print empty successor lists when they cannot be guessed"
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8451f3b13d900cfaaabd25fc3d5dc3f3d51832bf;p=llvm

Revert "[MIRPrinter] Print empty successor lists when they cannot be guessed"

This reverts commit r313685.

I thought I had ran ninja check, but apparently I didn't...
Need to update a bunch of mir tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313686 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/MIRPrinter.cpp b/lib/CodeGen/MIRPrinter.cpp
index 6347e6da942..db9ccef8a36 100644
--- a/lib/CodeGen/MIRPrinter.cpp
+++ b/lib/CodeGen/MIRPrinter.cpp
@@ -598,7 +598,8 @@ void MIPrinter::print(const MachineBasicBlock &MBB) {
   bool HasLineAttributes = false;
   // Print the successors
   bool canPredictProbs = canPredictBranchProbabilities(MBB);
-  if (!SimplifyMIR || !canPredictProbs || !canPredictSuccessors(MBB)) {
+  if (!MBB.succ_empty() && (!SimplifyMIR || !canPredictProbs ||
+                            !canPredictSuccessors(MBB))) {
     OS.indent(2) << "successors: ";
     for (auto I = MBB.succ_begin(), E = MBB.succ_end(); I != E; ++I) {
       if (I != MBB.succ_begin())
diff --git a/test/CodeGen/MIR/X86/unreachable_block.ll b/test/CodeGen/MIR/X86/unreachable_block.ll
deleted file mode 100644
index 4cea0392255..00000000000
--- a/test/CodeGen/MIR/X86/unreachable_block.ll
+++ /dev/null
@@ -1,48 +0,0 @@
-; RUN: llc -mtriple x86_64-- -stop-before peephole-opt -o %t.mir %s
-; RUN: llc -mtriple x86_64-- -run-pass none %t.mir -verify-machineinstrs -o - | FileCheck %s
-
-; Unreachable blocks in the machine instr representation are these
-; weird empty blocks with no successors.
-; The MIR printer used to not print empty lists of successors. However,
-; the MIR parser now treats non-printed list of successors as "please
-; guess it for me". As a result, the parser tries to guess the list of
-; successors and given the block is empty, just assumes it falls through
-; the next block.
-;
-; The following test case used to fail the verifier because the false
-; path ended up falling through split.true and now, the definition of
-; %v does not dominate all its uses.
-; Indeed, we go from the following CFG:
-;          entry
-;         /      \
-;    true (def)   false
-;        |
-;  split.true (use)
-;
-; To this one:
-;          entry
-;         /      \
-;    true (def)   false
-;        |        /  <-- invalid edge
-;  split.true (use)
-;
-; Because of the invalid edge, we get the "def does not
-; dominate all uses" error.
-;
-; CHECK-LABEL: name: foo
-; CHECK-LABEL: bb.{{[0-9]+}}.false:
-; CHECK-NEXT: successors:
-; CHECK-NOT: %bb.{{[0-9]+}}.split.true
-; CHECK-LABEL: bb.{{[0-9]+}}.split.true:
-define void @foo(i32* %bar) {
-  br i1 undef, label %true, label %false
-true:
-  %v = load i32, i32* %bar
-  br label %split.true
-false:
-  unreachable
-split.true:
-  %vInc = add i32 %v, 1
-  store i32 %vInc, i32* %bar
-  ret void
-}