[PATCH] D40711: [TwoAddressInstructionPass] Bugfix in handling of sunk instructions.
Jonas Paulsson via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 1 03:56:51 PST 2017
jonpa created this revision.
An instruction returned by TII->convertToThreeAddress() may contain a %noreg
(undef) operand, which is not expected by tryInstructionTransform(). So if
this MI is sunk to a lower point in MBB, it must be skipped when later
encountered.
A new set SunkInstrs is used for this purpose.
Note: there is no test supplied here, as this was triggered on SystemZ while
working on a review of instruction flags. A test case for this bugfix will be
included in the upcoming SystemZ commit.
https://reviews.llvm.org/D40711
Files:
lib/CodeGen/TwoAddressInstructionPass.cpp
Index: lib/CodeGen/TwoAddressInstructionPass.cpp
===================================================================
--- lib/CodeGen/TwoAddressInstructionPass.cpp
+++ lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -110,6 +110,10 @@
// Set of already processed instructions in the current block.
SmallPtrSet<MachineInstr*, 8> Processed;
+ // Set of instructions converted to three-address by target and then sunk
+ // down current basic block.
+ SmallPtrSet<MachineInstr*, 8> SunkInstrs;
+
// A map from virtual registers to physical registers which are likely targets
// to be coalesced to due to copies from physical registers to virtual
// registers. e.g. v1024 = move r0.
@@ -756,6 +760,8 @@
mi = NewMI;
nmi = std::next(mi);
}
+ else
+ SunkInstrs.insert(NewMI);
// Update source and destination register maps.
SrcRegMap.erase(RegA);
@@ -1674,10 +1680,13 @@
SrcRegMap.clear();
DstRegMap.clear();
Processed.clear();
+ SunkInstrs.clear();
for (MachineBasicBlock::iterator mi = MBB->begin(), me = MBB->end();
mi != me; ) {
MachineBasicBlock::iterator nmi = std::next(mi);
- if (mi->isDebugValue()) {
+ // Don't revisit an instruction previously converted by target. It may
+ // contain undef register operands (%noreg), which are not handled.
+ if (mi->isDebugValue() || SunkInstrs.count(&*mi)) {
mi = nmi;
continue;
}
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