[PATCH] D33839: Prevent outlining of basicblock that uses BlockAddress
serge via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 19 00:17:11 PDT 2017
serge-sans-paille updated this revision to Diff 102992.
serge-sans-paille retitled this revision from "Correctly remap BlockAddress when using CodeExtractor" to "Prevent outlining of basicblock that uses BlockAddress".
serge-sans-paille edited the summary of this revision.
Repository:
rL LLVM
https://reviews.llvm.org/D33839
Files:
../lib/Transforms/Utils/CodeExtractor.cpp
../test/Transforms/CodeExtractor/BlockAddressreference.ll
Index: ../test/Transforms/CodeExtractor/BlockAddressreference.ll
===================================================================
--- ../test/Transforms/CodeExtractor/BlockAddressreference.ll
+++ ../test/Transforms/CodeExtractor/BlockAddressreference.ll
@@ -0,0 +1,36 @@
+; RUN: opt < %s -loop-extract -S | FileCheck %s
+
+ at label = common local_unnamed_addr global i8* null
+
+; CHECK: define
+; no outlined function
+; CHECK-NOT: define
+define i32 @sterix(i32 %n) {
+entry:
+ %tobool = icmp ne i32 %n, 0
+ ; this blockaddress references a basic block that goes in the extracted loop
+ %cond = select i1 %tobool, i8* blockaddress(@sterix, %for.cond), i8* blockaddress(@sterix, %exit)
+ store i8* %cond, i8** @label
+ %cmp5 = icmp sgt i32 %n, 0
+ br i1 %cmp5, label %for.body, label %exit
+
+for.cond:
+ %mul = shl nsw i32 %s.06, 1
+ %exitcond = icmp eq i32 %inc, %n
+ br i1 %exitcond, label %exit.loopexit, label %for.body
+
+for.body:
+ %i.07 = phi i32 [ %inc, %for.cond ], [ 0, %entry ]
+ %s.06 = phi i32 [ %mul, %for.cond ], [ 1, %entry ]
+ %inc = add nuw nsw i32 %i.07, 1
+ br label %for.cond
+
+exit.loopexit:
+ %phitmp = icmp ne i32 %s.06, 2
+ %phitmp8 = zext i1 %phitmp to i32
+ br label %exit
+
+exit:
+ %s.1 = phi i32 [ 1, %entry ], [ %phitmp8, %exit.loopexit ]
+ ret i32 %s.1
+}
Index: ../lib/Transforms/Utils/CodeExtractor.cpp
===================================================================
--- ../lib/Transforms/Utils/CodeExtractor.cpp
+++ ../lib/Transforms/Utils/CodeExtractor.cpp
@@ -60,6 +60,33 @@
if (BB.isEHPad())
return false;
+ // taking the address of a basic block moved to another function is illegal
+ if (BB.hasAddressTaken())
+ return false;
+
+ // don't hoist code that uses another basicblock address, as it's likely to
+ // lead to unexpected behavior, like cross-function jumps
+ SmallPtrSet<User const *, 16> Visited;
+ SmallVector<User const *, 16> ToVisit;
+
+ for (Instruction const &Inst : BB)
+ ToVisit.push_back(&Inst);
+
+ // loop
+ while (!ToVisit.empty()) {
+ User const *Curr = ToVisit.pop_back_val();
+ if (Visited.count(Curr))
+ continue;
+ Visited.insert(Curr);
+ if (isa<BlockAddress const>(Curr)) {
+ return true; // even a reference to self is likely to be not compatible
+ }
+ for (auto const &U : Curr->operands()) {
+ if (auto *UU = dyn_cast<User>(U))
+ ToVisit.push_back(UU);
+ }
+ }
+
// Don't hoist code containing allocas, invokes, or vastarts.
for (BasicBlock::const_iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
if (isa<AllocaInst>(I) || isa<InvokeInst>(I))
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