[MemorySSA] Consider def-only BBs for live-in calculations.
If we have a BB with only MemoryDefs, live-in calculations will ignore
it. This means we get results like this:
define void @foo(i8* %p) {
; 1 = MemoryDef(liveOnEntry)
store i8 0, i8* %p
br i1 undef, label %if.then, label %if.end
if.then:
; 2 = MemoryDef(1)
store i8 1, i8* %p
br label %if.end
if.end:
; 3 = MemoryDef(1)
store i8 2, i8* %p
ret void
}
...When there should be a MemoryPhi in the `if.end` BB.
This patch fixes that behavior.
llvm-svn: 263991
diff --git a/llvm/lib/Transforms/Utils/MemorySSA.cpp b/llvm/lib/Transforms/Utils/MemorySSA.cpp
index f49d666..a794406 100644
--- a/llvm/lib/Transforms/Utils/MemorySSA.cpp
+++ b/llvm/lib/Transforms/Utils/MemorySSA.cpp
@@ -253,17 +253,13 @@
// Go through each block, figure out where defs occur, and chain together all
// the accesses.
for (BasicBlock &B : F) {
- bool InsertIntoDefUse = false;
bool InsertIntoDef = false;
AccessListType *Accesses = nullptr;
for (Instruction &I : B) {
MemoryUseOrDef *MUD = createNewAccess(&I, true);
if (!MUD)
continue;
- if (isa<MemoryDef>(MUD))
- InsertIntoDef = true;
- else
- InsertIntoDefUse = true;
+ InsertIntoDef |= isa<MemoryDef>(MUD);
if (!Accesses)
Accesses = getOrCreateAccessList(&B);
@@ -271,7 +267,7 @@
}
if (InsertIntoDef)
DefiningBlocks.insert(&B);
- if (InsertIntoDefUse)
+ if (Accesses)
DefUseBlocks.insert(&B);
}