[llvm] r276174 - [SCCP] Zap multiple return values.
Davide Italiano via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 20 13:17:13 PDT 2016
Author: davide
Date: Wed Jul 20 15:17:13 2016
New Revision: 276174
URL: http://llvm.org/viewvc/llvm-project?rev=276174&view=rev
Log:
[SCCP] Zap multiple return values.
We can replace the return values with undef if we replaced all
the call uses with a constant/undef.
Differential Revision: https://reviews.llvm.org/D22336
Added:
llvm/trunk/test/Transforms/SCCP/dont-zap-return.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll
Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=276174&r1=276173&r2=276174&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Wed Jul 20 15:17:13 2016
@@ -300,6 +300,12 @@ public:
return TrackedGlobals;
}
+ /// getMRVFunctionsTracked - Get the set of functions which return multiple
+ /// values tracked by the pass.
+ const SmallPtrSet<Function *, 16> getMRVFunctionsTracked() {
+ return MRVFunctionsTracked;
+ }
+
void markOverdefined(Value *V) {
assert(!V->getType()->isStructTy() &&
"structs should use markAnythingOverdefined");
@@ -316,6 +322,20 @@ public:
markOverdefined(V);
}
+ // isStructLatticeConstant - Return true if all the lattice values
+ // corresponding to elements of the structure are not overdefined,
+ // false otherwise.
+ bool isStructLatticeConstant(Function *F, StructType *STy) {
+ for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+ const auto &It = TrackedMultipleRetVals.find(std::make_pair(F, i));
+ assert(It != TrackedMultipleRetVals.end());
+ LatticeVal LV = It->second;
+ if (LV.isOverdefined())
+ return false;
+ }
+ return true;
+ }
+
private:
// pushToWorkList - Helper for markConstant/markForcedConstant
void pushToWorkList(LatticeVal &IV, Value *V) {
@@ -1690,6 +1710,19 @@ static bool AddressIsTaken(const GlobalV
return false;
}
+static void findReturnsToZap(Function &F,
+ SmallPtrSet<Function *, 32> &AddressTakenFunctions,
+ SmallVector<ReturnInst *, 8> &ReturnsToZap) {
+ // We can only do this if we know that nothing else can call the function.
+ if (!F.hasLocalLinkage() || AddressTakenFunctions.count(&F))
+ return;
+
+ for (BasicBlock &BB : F)
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
+ if (!isa<UndefValue>(RI->getOperand(0)))
+ ReturnsToZap.push_back(RI);
+}
+
static bool runIPSCCP(Module &M, const DataLayout &DL,
const TargetLibraryInfo *TLI) {
SCCPSolver Solver(DL, TLI);
@@ -1866,21 +1899,20 @@ static bool runIPSCCP(Module &M, const D
// whether other functions are optimizable.
SmallVector<ReturnInst*, 8> ReturnsToZap;
- // TODO: Process multiple value ret instructions also.
const DenseMap<Function*, LatticeVal> &RV = Solver.getTrackedRetVals();
for (const auto &I : RV) {
Function *F = I.first;
if (I.second.isOverdefined() || F->getReturnType()->isVoidTy())
continue;
+ findReturnsToZap(*F, AddressTakenFunctions, ReturnsToZap);
+ }
- // We can only do this if we know that nothing else can call the function.
- if (!F->hasLocalLinkage() || AddressTakenFunctions.count(F))
- continue;
-
- for (BasicBlock &BB : *F)
- if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
- if (!isa<UndefValue>(RI->getOperand(0)))
- ReturnsToZap.push_back(RI);
+ for (const auto &F : Solver.getMRVFunctionsTracked()) {
+ assert(F->getReturnType()->isStructTy() &&
+ "The return type should be a struct");
+ StructType *STy = cast<StructType>(F->getReturnType());
+ if (Solver.isStructLatticeConstant(F, STy))
+ findReturnsToZap(*F, AddressTakenFunctions, ReturnsToZap);
}
// Zap all returns which we've identified as zap to change.
Added: llvm/trunk/test/Transforms/SCCP/dont-zap-return.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/dont-zap-return.ll?rev=276174&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/dont-zap-return.ll (added)
+++ llvm/trunk/test/Transforms/SCCP/dont-zap-return.ll Wed Jul 20 15:17:13 2016
@@ -0,0 +1,24 @@
+; RUN: opt -ipsccp < %s -S | FileCheck %s
+
+define internal {i32, i32} @identity(i32 %patatino) {
+ %foo = insertvalue {i32, i32} {i32 1, i32 undef}, i32 %patatino, 1
+ ret {i32, i32} %foo
+}
+
+; Check that the return value is not transformed to undef
+; CHECK: define internal { i32, i32 } @identity(i32 %patatino) {
+; CHECK-NEXT: %foo = insertvalue { i32, i32 } { i32 1, i32 undef }, i32 %patatino, 1
+; CHECK-NEXT: ret { i32, i32 } %foo
+; CHECK-NEXT: }
+
+
+define {i32, i32} @caller(i32 %pat) {
+ %S1 = call {i32, i32} @identity(i32 %pat)
+ ret {i32, i32} %S1
+}
+
+; Check that we don't invent values and propagate them.
+; CHECK: define { i32, i32 } @caller(i32 %pat) {
+; CHECK-NEXT: %S1 = call { i32, i32 } @identity(i32 %pat)
+; CHECK-NEXT: ret { i32, i32 } %S1
+; CHECK-NEXT: }
Modified: llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll?rev=276174&r1=276173&r2=276174&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll (original)
+++ llvm/trunk/test/Transforms/SCCP/ipsccp-basic.ll Wed Jul 20 15:17:13 2016
@@ -83,7 +83,7 @@ define internal {i64,i64} @test4a() {
}
; CHECK-LABEL: define internal { i64, i64 } @test4a(
-; CHECK-NEXT: ret { i64, i64 } { i64 5, i64 4 }
+; CHECK-NEXT: ret { i64, i64 } undef
; CHECK-NEXT: }
define i64 @test4b() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
@@ -167,7 +167,7 @@ define internal %T @test7a(i32 %A) {
%mrv1 = insertvalue %T %mrv0, i32 %A, 1
ret %T %mrv1
; CHECK-LABEL: @test7a(
-; CHECK-NEXT: ret %T { i32 18, i32 17 }
+; CHECK-NEXT: ret %T undef
}
define i32 @test7b() {
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