[Attributor] Use the delete API for liveness

Johannes Doerfert · Johannes Doerfert · commit b19cd27b2843 · 2019-09-03T20:42:16.000Z
Reviewers: uenoku, sstefan1 Subscribers: hiraditya, bollu, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D66833 llvm-svn: 370818
diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -1868,7 +1868,7 @@ struct AAIsDeadImpl : public AAIsDead {
     Function &F = *getAssociatedFunction();
 
     if (AssumedLiveBlocks.empty()) {
-      F.replaceAllUsesWith(UndefValue::get(F.getType()));
+      A.deleteAfterManifest(F);
       return ChangeStatus::CHANGED;
     }
 
@@ -1918,6 +1918,9 @@ struct AAIsDeadImpl : public AAIsDead {
             }
           }
         }
+
+        if (SplitPos == &NormalDestBB->front())
+          AssumedLiveBlocks.insert(NormalDestBB);
       }
 
       BB = SplitPos->getParent();
@@ -1926,6 +1929,10 @@ struct AAIsDeadImpl : public AAIsDead {
       HasChanged = ChangeStatus::CHANGED;
     }
 
+    for (BasicBlock &BB : F)
+      if (!AssumedLiveBlocks.count(&BB))
+        A.deleteAfterManifest(BB);
+
     return HasChanged;
   }
 
@@ -3309,14 +3316,18 @@ ChangeStatus Attributor::run() {
                     << " blocks and " << ToBeDeletedInsts.size()
                     << " instructions\n");
   for (Instruction *I : ToBeDeletedInsts) {
-    if (I->hasNUsesOrMore(1))
+    if (!I->use_empty())
       I->replaceAllUsesWith(UndefValue::get(I->getType()));
     I->eraseFromParent();
   }
-  for (BasicBlock *BB : ToBeDeletedBlocks) {
-    // TODO: Check if we need to replace users (PHIs, indirect branches?)
-    BB->eraseFromParent();
+
+  if (unsigned NumDeadBlocks = ToBeDeletedBlocks.size()) {
+    SmallVector<BasicBlock *, 8> ToBeDeletedBBs;
+    ToBeDeletedBBs.reserve(NumDeadBlocks);
+    ToBeDeletedBBs.append(ToBeDeletedBlocks.begin(), ToBeDeletedBlocks.end());
+    DeleteDeadBlocks(ToBeDeletedBBs);
   }
+
   for (Function *Fn : ToBeDeletedFunctions) {
     Fn->replaceAllUsesWith(UndefValue::get(Fn->getType()));
     Fn->eraseFromParent();
diff --git a/llvm/test/Transforms/FunctionAttrs/arg_returned.ll b/llvm/test/Transforms/FunctionAttrs/arg_returned.ll
@@ -804,10 +804,8 @@ attributes #0 = { noinline nounwind uwtable }
 ; BOTH-DAG: attributes #{{[0-9]*}} = { nofree noinline nosync nounwind readnone uwtable }
 ; BOTH-DAG: attributes #{{[0-9]*}} = { nofree noinline noreturn nosync nounwind readonly uwtable }
 ; BOTH-DAG: attributes #{{[0-9]*}} = { noinline nounwind uwtable }
-; BOTH-DAG: attributes #{{[0-9]*}} = { nofree noinline nosync nounwind readnone uwtable willreturn }
-; BOTH-DAG: attributes #{{[0-9]*}} = { nofree noinline nosync nounwind uwtable willreturn }
+; BOTH-DAG: attributes #{{[0-9]*}} = { noreturn }
 ; BOTH-DAG: attributes #{{[0-9]*}} = { nofree nosync willreturn }
 ; BOTH-DAG: attributes #{{[0-9]*}} = { nofree nosync }
 ; BOTH-DAG: attributes #{{[0-9]*}} = { nofree noreturn nosync }
-; BOTH-DAG: attributes #{{[0-9]*}} = { noreturn }
 ; BOTH-NOT: attributes #
diff --git a/llvm/test/Transforms/FunctionAttrs/liveness.ll b/llvm/test/Transforms/FunctionAttrs/liveness.ll
@@ -15,7 +15,7 @@ declare i32 @bar() nosync readnone
 ; This internal function has no live call sites, so all its BBs are considered dead,
 ; and nothing should be deduced for it.
 
-; CHECK: define internal i32 @dead_internal_func(i32 %0)
+; CHECK-NOT: define internal i32 @dead_internal_func(i32 %0)
 define internal i32 @dead_internal_func(i32 %0) {
   %2 = icmp slt i32 %0, 1
   br i1 %2, label %3, label %5
@@ -56,14 +56,13 @@ entry:
   call void @no_return_call()
   ; CHECK: call void @no_return_call()
   ; CHECK-NEXT: unreachable
+  ; CHECK-NEXT: }
   call i32 @dead_internal_func(i32 10)
-  ; CHECK call i32 undef(i32 10)
   %cmp = icmp eq i32 %a, 0
   br i1 %cmp, label %cond.true, label %cond.false
 
 cond.true:                                        ; preds = %entry
   call i32 @internal_load(i32* %ptr2)
-  ; CHECK: call i32 @internal_load(i32* %ptr2)
   %load = call i32 @volatile_load(i32* %ptr1)
   call void @normal_call()
   %call = call i32 @foo()
@@ -104,6 +103,8 @@ cond.false:                                       ; preds = %entry
   br label %cond.end
 
 cond.end:                                         ; preds = %cond.false, %cond.true
+; CHECK:      cond.end:
+; CHECK-NEXT:   ret i32 %call1
   %cond = phi i32 [ %call, %cond.true ], [ %call1, %cond.false ]
   ret i32 %cond
 }
@@ -120,7 +121,7 @@ cond.true:                                        ; preds = %entry
   ; CHECK: call void @no_return_call()
   ; CHECK-NEXT: unreachable
   call i32 @dead_internal_func(i32 10)
-  ; CHECK call i32 undef(i32 10)
+  ; CHECK-NOT: call
   %call = call i32 @foo()
   br label %cond.end
 
@@ -129,7 +130,7 @@ cond.false:                                       ; preds = %entry
   ; CHECK: call void @no_return_call()
   ; CHECK-NEXT: unreachable
   call i32 @dead_internal_func(i32 10)
-  ; CHECK call i32 undef(i32 10)
+  ; CHECK-NEXT: }
   %call1 = call i32 @bar()
   br label %cond.end
 
@@ -215,9 +216,7 @@ cond.true:                                        ; preds = %entry
   ; CHECK-NEXT: call i32 @foo_noreturn_nounwind()
   ; CHECK-NEXT: unreachable
 
-  ; We keep the invoke around as other attributes might have references to it.
-  ; CHECK:       cond.true.split:                                  ; No predecessors!
-  ; CHECK-NEXT:      invoke i32 @foo_noreturn_nounwind()
+  ; CHECK-NOT:      @foo_noreturn_nounwind()
 
 cond.false:                                       ; preds = %entry
   call void @normal_call()

Original file line number	Diff line number	Diff line change
`@@ -1868,7 +1868,7 @@ struct AAIsDeadImpl : public AAIsDead {`
`1868`	`1868`	`Function &F = *getAssociatedFunction();`
`1869`	`1869`
`1870`	`1870`	`if (AssumedLiveBlocks.empty()) {`
`1871`		`- F.replaceAllUsesWith(UndefValue::get(F.getType()));`
	`1871`	`+ A.deleteAfterManifest(F);`
`1872`	`1872`	`return ChangeStatus::CHANGED;`
`1873`	`1873`	`}`
`1874`	`1874`
`@@ -1918,6 +1918,9 @@ struct AAIsDeadImpl : public AAIsDead {`
`1918`	`1918`	`}`
`1919`	`1919`	`}`
`1920`	`1920`	`}`
	`1921`	`+`
	`1922`	`+ if (SplitPos == &NormalDestBB->front())`
	`1923`	`+ AssumedLiveBlocks.insert(NormalDestBB);`
`1921`	`1924`	`}`
`1922`	`1925`
`1923`	`1926`	`BB = SplitPos->getParent();`
`@@ -1926,6 +1929,10 @@ struct AAIsDeadImpl : public AAIsDead {`
`1926`	`1929`	`HasChanged = ChangeStatus::CHANGED;`
`1927`	`1930`	`}`
`1928`	`1931`
	`1932`	`+ for (BasicBlock &BB : F)`
	`1933`	`+ if (!AssumedLiveBlocks.count(&BB))`
	`1934`	`+ A.deleteAfterManifest(BB);`
	`1935`	`+`
`1929`	`1936`	`return HasChanged;`
`1930`	`1937`	`}`
`1931`	`1938`
`@@ -3309,14 +3316,18 @@ ChangeStatus Attributor::run() {`
`3309`	`3316`	`<< " blocks and " << ToBeDeletedInsts.size()`
`3310`	`3317`	`<< " instructions\n");`
`3311`	`3318`	`for (Instruction *I : ToBeDeletedInsts) {`
`3312`		`- if (I->hasNUsesOrMore(1))`
	`3319`	`+ if (!I->use_empty())`
`3313`	`3320`	`I->replaceAllUsesWith(UndefValue::get(I->getType()));`
`3314`	`3321`	`I->eraseFromParent();`
`3315`	`3322`	`}`
`3316`		`- for (BasicBlock *BB : ToBeDeletedBlocks) {`
`3317`		`- // TODO: Check if we need to replace users (PHIs, indirect branches?)`
`3318`		`- BB->eraseFromParent();`
	`3323`	`+`
	`3324`	`+ if (unsigned NumDeadBlocks = ToBeDeletedBlocks.size()) {`
	`3325`	`+ SmallVector<BasicBlock *, 8> ToBeDeletedBBs;`
	`3326`	`+ ToBeDeletedBBs.reserve(NumDeadBlocks);`
	`3327`	`+ ToBeDeletedBBs.append(ToBeDeletedBlocks.begin(), ToBeDeletedBlocks.end());`
	`3328`	`+ DeleteDeadBlocks(ToBeDeletedBBs);`
`3319`	`3329`	`}`
	`3330`	`+`
`3320`	`3331`	`for (Function *Fn : ToBeDeletedFunctions) {`
`3321`	`3332`	`Fn->replaceAllUsesWith(UndefValue::get(Fn->getType()));`
`3322`	`3333`	`Fn->eraseFromParent();`