Changes in directory llvm/lib/CodeGen:
IfConversion.cpp updated: 1.3 -> 1.4
---
Log message:
isBlockPredicable() always ignore terminal instructions; add comments.
---
Diffs of the changes: (+23 -13)
IfConversion.cpp | 36 +++++++++++++++++++++++-------------
1 files changed, 23 insertions(+), 13 deletions(-)
Index: llvm/lib/CodeGen/IfConversion.cpp
diff -u llvm/lib/CodeGen/IfConversion.cpp:1.3
llvm/lib/CodeGen/IfConversion.cpp:1.4
--- llvm/lib/CodeGen/IfConversion.cpp:1.3 Wed May 16 15:56:08 2007
+++ llvm/lib/CodeGen/IfConversion.cpp Wed May 16 16:54:37 2007
@@ -68,8 +68,7 @@
std::vector<int> &Candidates);
bool IfConvertDiamond(BBInfo &BBI);
bool IfConvertTriangle(BBInfo &BBI);
- bool isBlockPredicable(MachineBasicBlock *BB,
- bool IgnoreTerm = false) const;
+ bool isBlockPredicable(MachineBasicBlock *BB) const;
void PredicateBlock(MachineBasicBlock *BB,
std::vector<MachineOperand> &Cond,
bool IgnoreTerm = false);
@@ -134,15 +133,19 @@
if (TII->AnalyzeBranch(*BB, BBI.TBB, BBI.FBB, BBI.Cond)
|| !BBI.TBB || BBI.Cond.size() == 0)
return;
+ // Can't do it if 'true' block is already marked as to be if-converted.
AnalyzeBlock(BBI.TBB);
BBInfo &TBBI = BBAnalysis[BBI.TBB->getNumber()];
if (TBBI.Kind != ICNotClassfied)
return;
-
+
+ // No false branch. This BB must end with a conditional branch and a
+ // fallthrough.
if (!BBI.FBB)
BBI.FBB = findFalseBlock(BB, BBI.TBB);
assert(BBI.FBB && "Expected to find the fallthrough block!");
+ // Can't do it if 'false' block is already marked as to be if-converted.
AnalyzeBlock(BBI.FBB);
BBInfo &FBBI = BBAnalysis[BBI.FBB->getNumber()];
if (FBBI.Kind != ICNotClassfied)
@@ -178,6 +181,8 @@
return;
}
+/// InitialFunctionAnalysis - Analyze all blocks and find entries for all
+/// if-conversion candidates.
void IfConverter::InitialFunctionAnalysis(MachineFunction &MF,
std::vector<int> &Candidates) {
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
@@ -189,8 +194,10 @@
}
}
+/// IfConvertTriangle - If convert a triangle sub-CFG.
+///
bool IfConverter::IfConvertTriangle(BBInfo &BBI) {
- if (isBlockPredicable(BBI.TBB, true)) {
+ if (isBlockPredicable(BBI.TBB)) {
// Predicate the 'true' block after removing its branch.
TII->RemoveBranch(*BBI.TBB);
PredicateBlock(BBI.TBB, BBI.Cond);
@@ -213,9 +220,10 @@
return false;
}
+/// IfConvertDiamond - If convert a diamond sub-CFG.
+///
bool IfConverter::IfConvertDiamond(BBInfo &BBI) {
- if (isBlockPredicable(BBI.TBB, true) &&
- isBlockPredicable(BBI.FBB, true)) {
+ if (isBlockPredicable(BBI.TBB) && isBlockPredicable(BBI.FBB)) {
std::vector<MachineInstr*> Dups;
if (!BBI.CMBB) {
// No common merge block. Check if the terminators (e.g. return) are
@@ -230,7 +238,8 @@
++TT;
++FT;
}
-
+ // One of the two pathes have more terminators, make sure they are all
+ // predicable.
while (TT != BBI.TBB->end())
if (!TT->isPredicable())
return false; // Can't if-convert. Abort!
@@ -272,13 +281,11 @@
/// isBlockPredicable - Returns true if the block is predicable. In most
/// cases, that means all the instructions in the block has M_PREDICABLE flag.
-/// If IgnoreTerm is true, assume all the terminator instructions can be
-/// converted or deleted.
-bool IfConverter::isBlockPredicable(MachineBasicBlock *BB,
- bool IgnoreTerm) const {
+/// It assume all the terminator instructions can be converted or deleted.
+bool IfConverter::isBlockPredicable(MachineBasicBlock *BB) const {
for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
I != E; ++I) {
- if (IgnoreTerm && TII->isTerminatorInstr(I->getOpcode()))
+ if (TII->isTerminatorInstr(I->getOpcode()))
continue;
if (!I->isPredicable())
return false;
@@ -295,7 +302,10 @@
I != E; ++I) {
if (IgnoreTerm && TII->isTerminatorInstr(I->getOpcode()))
continue;
- TII->PredicateInstruction(&*I, Cond);
+ if (!TII->PredicateInstruction(&*I, Cond)) {
+ cerr << "Unable to predication " << *I << "!\n";
+ abort();
+ }
}
}
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