[PATCH] D78823: [llvm][CodeGen] Check for memory instructions when querying for alias status
Jean-Michel Gorius via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Apr 24 12:26:42 PDT 2020
Kayjukh created this revision.
Kayjukh added reviewers: hfinkel, t.p.northover, mcrosier, eli.friedman.
Herald added subscribers: llvm-commits, hiraditya, kristof.beyls.
Herald added a project: LLVM.
Add a check to make sure that MachineInstr::mayAlias returns prematurely if at least one of its instruction parameters does not access memory. This prevents calls to TargetInstrInfo::areMemAccessesTriviallyDisjoint with incompatible instructions.
A side effect of this change is to render the mayAlias helper in the AArch64 load/store optimizer obsolete. We can now directly call the MachineInstr::mayAlias member function.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D78823
Files:
llvm/lib/CodeGen/MachineInstr.cpp
llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
Index: llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ llvm/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -1144,24 +1144,11 @@
return (Num + PowOf2 - 1) & ~(PowOf2 - 1);
}
-static bool mayAlias(MachineInstr &MIa, MachineInstr &MIb,
- AliasAnalysis *AA) {
- // One of the instructions must modify memory.
- if (!MIa.mayStore() && !MIb.mayStore())
- return false;
-
- // Both instructions must be memory operations.
- if (!MIa.mayLoadOrStore() && !MIb.mayLoadOrStore())
- return false;
-
- return MIa.mayAlias(AA, MIb, /*UseTBAA*/false);
-}
-
static bool mayAlias(MachineInstr &MIa,
SmallVectorImpl<MachineInstr *> &MemInsns,
AliasAnalysis *AA) {
for (MachineInstr *MIb : MemInsns)
- if (mayAlias(MIa, *MIb, AA))
+ if (MIa.mayAlias(AA, *MIb, /*UseTBAA*/ false))
return true;
return false;
@@ -1219,7 +1206,7 @@
return false;
// If we encounter a store aliased with the load, return early.
- if (MI.mayStore() && mayAlias(LoadMI, MI, AA))
+ if (MI.mayStore() && LoadMI.mayAlias(AA, MI, /*UseTBAA*/ false))
return false;
} while (MBBI != B && Count < Limit);
return false;
Index: llvm/lib/CodeGen/MachineInstr.cpp
===================================================================
--- llvm/lib/CodeGen/MachineInstr.cpp
+++ llvm/lib/CodeGen/MachineInstr.cpp
@@ -1220,6 +1220,10 @@
if (!mayStore() && !Other.mayStore())
return false;
+ // Both instructions must be memory operations to be able to alias.
+ if (!mayLoadOrStore() || !Other.mayLoadOrStore())
+ return false;
+
// Let the target decide if memory accesses cannot possibly overlap.
if (TII->areMemAccessesTriviallyDisjoint(*this, Other))
return false;
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