MIParser/MIRPrinter: Compute block successors if not explicitely specified
- MIParser: If the successor list is not specified successors will be
added based on basic block operands in the block and possible
fallthrough.
- MIRPrinter: Adds a new `simplify-mir` option, with that option set:
Skip printing of block successor lists in cases where the
parser is guaranteed to reconstruct it. This means we still print the
list if some successor cannot be determined (happens for example for
jump tables), if the successor order changes or branch probabilities
being unequal.
Differential Revision: https://reviews.llvm.org/D31262
llvm-svn: 302289
diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
index cac22af..1d36ff4 100644
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -12,11 +12,13 @@
//===----------------------------------------------------------------------===//
#include "MIParser.h"
+
#include "MILexer.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/AsmParser/SlotMapping.h"
+#include "llvm/CodeGen/MIRPrinter.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
@@ -134,7 +136,8 @@
bool
parseBasicBlockDefinition(DenseMap<unsigned, MachineBasicBlock *> &MBBSlots);
- bool parseBasicBlock(MachineBasicBlock &MBB);
+ bool parseBasicBlock(MachineBasicBlock &MBB,
+ MachineBasicBlock *&AddFalthroughFrom);
bool parseBasicBlockLiveins(MachineBasicBlock &MBB);
bool parseBasicBlockSuccessors(MachineBasicBlock &MBB);
@@ -518,7 +521,8 @@
return false;
}
-bool MIParser::parseBasicBlock(MachineBasicBlock &MBB) {
+bool MIParser::parseBasicBlock(MachineBasicBlock &MBB,
+ MachineBasicBlock *&AddFalthroughFrom) {
// Skip the definition.
assert(Token.is(MIToken::MachineBasicBlockLabel));
lex();
@@ -538,10 +542,12 @@
//
// is equivalent to
// liveins: %edi, %esi
+ bool ExplicitSuccesors = false;
while (true) {
if (Token.is(MIToken::kw_successors)) {
if (parseBasicBlockSuccessors(MBB))
return true;
+ ExplicitSuccesors = true;
} else if (Token.is(MIToken::kw_liveins)) {
if (parseBasicBlockLiveins(MBB))
return true;
@@ -557,10 +563,9 @@
// Parse the instructions.
bool IsInBundle = false;
MachineInstr *PrevMI = nullptr;
- while (true) {
- if (Token.is(MIToken::MachineBasicBlockLabel) || Token.is(MIToken::Eof))
- return false;
- else if (consumeIfPresent(MIToken::Newline))
+ while (!Token.is(MIToken::MachineBasicBlockLabel) &&
+ !Token.is(MIToken::Eof)) {
+ if (consumeIfPresent(MIToken::Newline))
continue;
if (consumeIfPresent(MIToken::rbrace)) {
// The first parsing pass should verify that all closing '}' have an
@@ -592,6 +597,22 @@
assert(Token.isNewlineOrEOF() && "MI is not fully parsed");
lex();
}
+
+ // Construct successor list by searching for basic block machine operands.
+ if (!ExplicitSuccesors) {
+ SmallVector<MachineBasicBlock*,4> Successors;
+ bool IsFallthrough;
+ guessSuccessors(MBB, Successors, IsFallthrough);
+ for (MachineBasicBlock *Succ : Successors)
+ MBB.addSuccessor(Succ);
+
+ if (IsFallthrough) {
+ AddFalthroughFrom = &MBB;
+ } else {
+ MBB.normalizeSuccProbs();
+ }
+ }
+
return false;
}
@@ -605,11 +626,18 @@
// The first parsing pass should have verified that this token is a MBB label
// in the 'parseBasicBlockDefinitions' method.
assert(Token.is(MIToken::MachineBasicBlockLabel));
+ MachineBasicBlock *AddFalthroughFrom = nullptr;
do {
MachineBasicBlock *MBB = nullptr;
if (parseMBBReference(MBB))
return true;
- if (parseBasicBlock(*MBB))
+ if (AddFalthroughFrom) {
+ if (!AddFalthroughFrom->isSuccessor(MBB))
+ AddFalthroughFrom->addSuccessor(MBB);
+ AddFalthroughFrom->normalizeSuccProbs();
+ AddFalthroughFrom = nullptr;
+ }
+ if (parseBasicBlock(*MBB, AddFalthroughFrom))
return true;
// The method 'parseBasicBlock' should parse the whole block until the next
// block or the end of file.