[llvm] r367430 - [IPSCCP] Move callsite check to the beginning of the loop.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 31 05:57:04 PDT 2019
Author: fhahn
Date: Wed Jul 31 05:57:04 2019
New Revision: 367430
URL: http://llvm.org/viewvc/llvm-project?rev=367430&view=rev
Log:
[IPSCCP] Move callsite check to the beginning of the loop.
We have some code marks instructions with struct operands as overdefined,
but if the instruction is a call to a function with tracked arguments,
this breaks the assumption that the lattice values of all call sites
are not overdefined and will be replaced by a constant.
This also re-adds the assertion from D65222, with additionally skipping
non-callsite uses. This patch should address the cases reported in which
the assertion fired.
Fixes PR42738.
Reviewers: efriedma, davide
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D65439
Added:
llvm/trunk/test/Transforms/SCCP/struct-arg-resolve-undefs.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
llvm/trunk/test/Transforms/SCCP/indirectbr.ll
Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=367430&r1=367429&r2=367430&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Wed Jul 31 05:57:04 2019
@@ -1465,7 +1465,24 @@ bool SCCPSolver::ResolvedUndefsIn(Functi
}
LatticeVal &LV = getValueState(&I);
- if (!LV.isUnknown()) continue;
+ if (!LV.isUnknown())
+ continue;
+
+ // There are two reasons a call can have an undef result
+ // 1. It could be tracked.
+ // 2. It could be constant-foldable.
+ // Because of the way we solve return values, tracked calls must
+ // never be marked overdefined in ResolvedUndefsIn.
+ if (CallSite CS = CallSite(&I)) {
+ if (Function *F = CS.getCalledFunction())
+ if (TrackedRetVals.count(F))
+ continue;
+
+ // If the call is constant-foldable, we mark it overdefined because
+ // we do not know what return values are valid.
+ markOverdefined(&I);
+ return true;
+ }
// extractvalue is safe; check here because the argument is a struct.
if (isa<ExtractValueInst>(I))
@@ -1638,19 +1655,7 @@ bool SCCPSolver::ResolvedUndefsIn(Functi
case Instruction::Call:
case Instruction::Invoke:
case Instruction::CallBr:
- // There are two reasons a call can have an undef result
- // 1. It could be tracked.
- // 2. It could be constant-foldable.
- // Because of the way we solve return values, tracked calls must
- // never be marked overdefined in ResolvedUndefsIn.
- if (Function *F = CallSite(&I).getCalledFunction())
- if (TrackedRetVals.count(F))
- break;
-
- // If the call is constant-foldable, we mark it overdefined because
- // we do not know what return values are valid.
- markOverdefined(&I);
- return true;
+ llvm_unreachable("Call-like instructions should have be handled early");
default:
// If we don't know what should happen here, conservatively mark it
// overdefined.
@@ -1924,6 +1929,27 @@ static void findReturnsToZap(Function &F
return;
}
+ assert(
+ all_of(F.users(),
+ [&Solver](User *U) {
+ if (isa<Instruction>(U) &&
+ !Solver.isBlockExecutable(cast<Instruction>(U)->getParent()))
+ return true;
+ // Non-callsite uses are not impacted by zapping. Also, constant
+ // uses (like blockaddresses) could stuck around, without being
+ // used in the underlying IR, meaning we do not have lattice
+ // values for them.
+ if (!CallSite(U))
+ return true;
+ if (U->getType()->isStructTy()) {
+ return all_of(
+ Solver.getStructLatticeValueFor(U),
+ [](const LatticeVal &LV) { return !LV.isOverdefined(); });
+ }
+ return !Solver.getLatticeValueFor(U).isOverdefined();
+ }) &&
+ "We can only zap functions where all live users have a concrete value");
+
for (BasicBlock &BB : F) {
if (CallInst *CI = BB.getTerminatingMustTailCall()) {
LLVM_DEBUG(dbgs() << "Can't zap return of the block due to present "
Modified: llvm/trunk/test/Transforms/SCCP/indirectbr.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/indirectbr.ll?rev=367430&r1=367429&r2=367430&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/indirectbr.ll (original)
+++ llvm/trunk/test/Transforms/SCCP/indirectbr.ll Wed Jul 31 05:57:04 2019
@@ -1,4 +1,4 @@
-; RUN: opt -S -sccp < %s | FileCheck %s
+; RUN: opt -S -ipsccp < %s | FileCheck %s
declare void @BB0_f()
declare void @BB1_f()
@@ -74,3 +74,35 @@ BB1:
}
+; CHECK-LABEL: define internal i32 @indbrtest5(
+; CHECK: ret i32 undef
+define internal i32 @indbrtest5(i1 %c) {
+entry:
+ br i1 %c, label %bb1, label %bb2
+
+bb1:
+ br label %branch.block
+
+
+bb2:
+ br label %branch.block
+
+branch.block:
+ %addr = phi i8* [blockaddress(@indbrtest5, %target1), %bb1], [blockaddress(@indbrtest5, %target2), %bb2]
+ indirectbr i8* %addr, [label %target1, label %target2]
+
+target1:
+ br label %target2
+
+target2:
+ ret i32 10
+}
+
+
+define i32 @indbrtest5_callee(i1 %c) {
+; CHECK-LABEL: define i32 @indbrtest5_callee(
+; CHECK-NEXT: %r = call i32 @indbrtest5(i1 %c)
+; CHECK-NEXT: ret i32 10
+ %r = call i32 @indbrtest5(i1 %c)
+ ret i32 %r
+}
Added: llvm/trunk/test/Transforms/SCCP/struct-arg-resolve-undefs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/struct-arg-resolve-undefs.ll?rev=367430&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/struct-arg-resolve-undefs.ll (added)
+++ llvm/trunk/test/Transforms/SCCP/struct-arg-resolve-undefs.ll Wed Jul 31 05:57:04 2019
@@ -0,0 +1,49 @@
+; RUN: opt -ipsccp -S %s | FileCheck %s
+
+%struct.S = type { i32 }
+
+
+define void @main() {
+; CHECK-LABEL: void @main() {
+; CHECK-NEXT: %r = call i32 @f(%struct.S { i32 100 })
+; CHECK-NEXT: call void @do_report(i32 123)
+ %r = call i32 @f(%struct.S { i32 100 })
+ call void @do_report(i32 %r)
+ ret void
+}
+
+declare void @do_report(i32)
+
+define internal i32 @f(%struct.S %s.coerce) {
+; CHECK-LABEL: define internal i32 @f(%struct.S %s.coerce)
+; CHECK-LABEL: entry:
+; CHECK-NEXT: %call = call i8 @lsh(i8 1, i32 100)
+; CHECK-LABEL: if.end:
+; CHECK-NEXT: ret i32 undef
+entry:
+ %ev = extractvalue %struct.S %s.coerce, 0
+ %call = call i8 @lsh(i8 1, i32 %ev)
+ %tobool = icmp ne i8 %call, 0
+ br i1 %tobool, label %for.cond, label %if.end
+
+for.cond: ; preds = %for.cond, %if.then
+ %i.0 = phi i32 [ 0, %entry], [ %inc, %for.cond ]
+ %cmp = icmp slt i32 %i.0, 1
+ %inc = add nsw i32 %i.0, 1
+ br i1 %cmp, label %for.cond, label %if.end
+
+if.end: ; preds = %for.cond, %entry
+ ret i32 123
+}
+
+define internal i8 @lsh(i8 %l, i32 %r) {
+entry:
+ %conv = sext i8 %l to i32
+ %cmp = icmp slt i32 %conv, 0
+ %shr = ashr i32 127, %r
+ %cmp4 = icmp sgt i32 %conv, %shr
+ %or.cond13 = or i1 %cmp, %cmp4
+ %cond = select i1 %or.cond13, i32 %conv, i32 0
+ %conv7 = trunc i32 %cond to i8
+ ret i8 %conv7
+}
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