// branch of the dominator tree first. This will guarantee this resets on
// the smallest set of blocks.
if (LocInfo.LowerBoundBlock && LocInfo.LowerBoundBlock != BB &&
- !DT->dominates(LocInfo.LowerBoundBlock, BB)){
+ !DT->dominates(LocInfo.LowerBoundBlock, BB)) {
// Reset the lower bound of things to check.
// TODO: Some day we should be able to reset to last kill, rather than
// 0.
}
void MemorySSA::placePHINodes(
- const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks,
- const SmallPtrSetImpl<BasicBlock *> &LiveInBlocks) {
+ const SmallPtrSetImpl<BasicBlock *> &DefiningBlocks) {
// Determine where our MemoryPhi's should go
ForwardIDFCalculator IDFs(*DT);
IDFs.setDefiningBlocks(DefiningBlocks);
- IDFs.setLiveInBlocks(LiveInBlocks);
SmallVector<BasicBlock *, 32> IDFBlocks;
IDFs.calculate(IDFBlocks);
if (Accesses)
DefUseBlocks.insert(&B);
}
-
- // Compute live-in.
- // Live in is normally defined as "all the blocks on the path from each def to
- // each of it's uses".
- // MemoryDef's are implicit uses of previous state, so they are also uses.
- // This means we don't really have def-only instructions. The only
- // MemoryDef's that are not really uses are those that are of the LiveOnEntry
- // variable (because LiveOnEntry can reach anywhere, and every def is a
- // must-kill of LiveOnEntry).
- // In theory, you could precisely compute live-in by using alias-analysis to
- // disambiguate defs and uses to see which really pair up with which.
- // In practice, this would be really expensive and difficult. So we simply
- // assume all defs are also uses that need to be kept live.
- // Because of this, the end result of this live-in computation will be "the
- // entire set of basic blocks that reach any use".
-
- SmallPtrSet<BasicBlock *, 32> LiveInBlocks;
- SmallVector<BasicBlock *, 64> LiveInBlockWorklist(DefUseBlocks.begin(),
- DefUseBlocks.end());
- // Now that we have a set of blocks where a value is live-in, recursively add
- // predecessors until we find the full region the value is live.
- while (!LiveInBlockWorklist.empty()) {
- BasicBlock *BB = LiveInBlockWorklist.pop_back_val();
-
- // The block really is live in here, insert it into the set. If already in
- // the set, then it has already been processed.
- if (!LiveInBlocks.insert(BB).second)
- continue;
-
- // Since the value is live into BB, it is either defined in a predecessor or
- // live into it to.
- LiveInBlockWorklist.append(pred_begin(BB), pred_end(BB));
- }
- placePHINodes(DefiningBlocks, LiveInBlocks);
+ placePHINodes(DefiningBlocks);
// Now do regular SSA renaming on the MemoryDef/MemoryUse. Visited will get
// filled in with all blocks.
char MemorySSAAnalysis::PassID;
-MemorySSAAnalysis::Result
-MemorySSAAnalysis::run(Function &F, FunctionAnalysisManager &AM) {
+MemorySSAAnalysis::Result MemorySSAAnalysis::run(Function &F,
+ FunctionAnalysisManager &AM) {
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
return MemorySSAAnalysis::Result(make_unique<MemorySSA>(F, &AA, &DT));
+++ /dev/null
-; RUN: opt -basicaa -print-memoryssa -verify-memoryssa -analyze < %s 2>&1 | FileCheck %s
-; RUN: opt -aa-pipeline=basic-aa -passes='print<memoryssa>,verify<memoryssa>' -disable-output < %s 2>&1 | FileCheck %s
-define void @F(i8*) {
- br i1 true, label %left, label %right
-left:
-; CHECK: 1 = MemoryDef(liveOnEntry)
- store i8 16, i8* %0
- br label %merge
-right:
- br label %merge
-
-merge:
-; CHECK-NOT: 2 = MemoryPhi
-ret void
-}
-
-define void @F2(i8*) {
- br i1 true, label %left, label %right
-left:
-; CHECK: 1 = MemoryDef(liveOnEntry)
- store i8 16, i8* %0
- br label %merge
-right:
- br label %merge
-
-merge:
-; CHECK: 2 = MemoryPhi({left,1},{right,liveOnEntry})
-%c = load i8, i8* %0
-ret void
-}
-
-; Ensure we treat def-only blocks as though they have uses for phi placement.
-; CHECK-LABEL: define void @F3
-define void @F3() {
- %a = alloca i8
-; CHECK: 1 = MemoryDef(liveOnEntry)
-; CHECK-NEXT: store i8 0, i8* %a
- store i8 0, i8* %a
- br i1 undef, label %if.then, label %if.end
-
-if.then:
-; CHECK: 2 = MemoryDef(1)
-; CHECK-NEXT: store i8 1, i8* %a
- store i8 1, i8* %a
- br label %if.end
-
-if.end:
-; CHECK: 4 = MemoryPhi({%0,1},{if.then,2})
-; CHECK: 3 = MemoryDef(4)
-; CHECK-NEXT: store i8 2, i8* %a
- store i8 2, i8* %a
- ret void
-}