[llvm] r275678 - Revert "Revert r275027 - Let FuncAttrs infer the 'returned' argument attribute"
Hal Finkel via llvm-commits
llvm-commits at lists.llvm.org
Sat Jul 16 00:21:28 PDT 2016
Author: hfinkel
Date: Sat Jul 16 02:21:28 2016
New Revision: 275678
URL: http://llvm.org/viewvc/llvm-project?rev=275678&view=rev
Log:
Revert "Revert r275027 - Let FuncAttrs infer the 'returned' argument attribute"
This reverts commit r275042; the initial commit triggered self-hosting failures
on ARM/AArch64. James Molloy identified the problematic backend code, which has
been disabled in r275677. Trying again...
Original commit message:
Let FuncAttrs infer the 'returned' argument attribute
A function can have one argument with the 'returned' attribute, indicating that
the associated argument is always the return value of the function. Add
FuncAttrs inference logic.
Modified:
llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
llvm/trunk/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll
llvm/trunk/test/Transforms/FunctionAttrs/nocapture.ll
llvm/trunk/test/Transforms/FunctionAttrs/readattrs.ll
Modified: llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp?rev=275678&r1=275677&r2=275678&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp Sat Jul 16 02:21:28 2016
@@ -42,6 +42,7 @@ using namespace llvm;
STATISTIC(NumReadNone, "Number of functions marked readnone");
STATISTIC(NumReadOnly, "Number of functions marked readonly");
STATISTIC(NumNoCapture, "Number of arguments marked nocapture");
+STATISTIC(NumReturned, "Number of arguments marked returned");
STATISTIC(NumReadNoneArg, "Number of arguments marked readnone");
STATISTIC(NumReadOnlyArg, "Number of arguments marked readonly");
STATISTIC(NumNoAlias, "Number of function returns marked noalias");
@@ -483,6 +484,53 @@ determinePointerReadAttrs(Argument *A,
return IsRead ? Attribute::ReadOnly : Attribute::ReadNone;
}
+/// Deduce returned attributes for the SCC.
+static bool addArgumentReturnedAttrs(const SCCNodeSet &SCCNodes) {
+ bool Changed = false;
+
+ AttrBuilder B;
+ B.addAttribute(Attribute::Returned);
+
+ // Check each function in turn, determining if an argument is always returned.
+ for (Function *F : SCCNodes) {
+ // We can infer and propagate function attributes only when we know that the
+ // definition we'll get at link time is *exactly* the definition we see now.
+ // For more details, see GlobalValue::mayBeDerefined.
+ if (!F->hasExactDefinition())
+ continue;
+
+ if (F->getReturnType()->isVoidTy())
+ continue;
+
+ auto FindRetArg = [&]() -> Value * {
+ Value *RetArg = nullptr;
+ for (BasicBlock &BB : *F)
+ if (auto *Ret = dyn_cast<ReturnInst>(BB.getTerminator())) {
+ // Note that stripPointerCasts should look through functions with
+ // returned arguments.
+ Value *RetVal = Ret->getReturnValue()->stripPointerCasts();
+ if (RetVal->getType() == F->getReturnType() && isa<Argument>(RetVal)) {
+ if (!RetArg)
+ RetArg = RetVal;
+ else if (RetArg != RetVal)
+ return nullptr;
+ }
+ }
+
+ return RetArg;
+ };
+
+ if (Value *RetArg = FindRetArg()) {
+ auto *A = cast<Argument>(RetArg);
+ A->addAttr(AttributeSet::get(F->getContext(), A->getArgNo() + 1, B));
+ ++NumReturned;
+ Changed = true;
+ }
+ }
+
+ return Changed;
+}
+
/// Deduce nocapture attributes for the SCC.
static bool addArgumentAttrs(const SCCNodeSet &SCCNodes) {
bool Changed = false;
@@ -1024,6 +1072,7 @@ PreservedAnalyses PostOrderFunctionAttrs
}
bool Changed = false;
+ Changed |= addArgumentReturnedAttrs(SCCNodes);
Changed |= addReadAttrs(SCCNodes, AARGetter);
Changed |= addArgumentAttrs(SCCNodes);
@@ -1089,6 +1138,7 @@ static bool runImpl(CallGraphSCC &SCC, A
SCCNodes.insert(F);
}
+ Changed |= addArgumentReturnedAttrs(SCCNodes);
Changed |= addReadAttrs(SCCNodes, AARGetter);
Changed |= addArgumentAttrs(SCCNodes);
Modified: llvm/trunk/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll?rev=275678&r1=275677&r2=275678&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll (original)
+++ llvm/trunk/test/Transforms/FunctionAttrs/2009-01-02-LocalStores.ll Sat Jul 16 02:21:28 2016
@@ -14,7 +14,7 @@ define i32* @b(i32 *%q) {
ret i32* %tmp
}
-; CHECK: define i32* @c(i32* readnone %r)
+; CHECK: define i32* @c(i32* readnone returned %r)
@g = global i32 0
define i32* @c(i32 *%r) {
%a = icmp eq i32* %r, null
Modified: llvm/trunk/test/Transforms/FunctionAttrs/nocapture.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/nocapture.ll?rev=275678&r1=275677&r2=275678&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/nocapture.ll (original)
+++ llvm/trunk/test/Transforms/FunctionAttrs/nocapture.ll Sat Jul 16 02:21:28 2016
@@ -1,7 +1,7 @@
; RUN: opt < %s -functionattrs -S | FileCheck %s
@g = global i32* null ; <i32**> [#uses=1]
-; CHECK: define i32* @c1(i32* readnone %q)
+; CHECK: define i32* @c1(i32* readnone returned %q)
define i32* @c1(i32* %q) {
ret i32* %q
}
@@ -140,7 +140,7 @@ define void @test1_1(i8* %x1_1, i8* %y1_
ret void
}
-; CHECK: define i8* @test1_2(i8* nocapture readnone %x1_2, i8* %y1_2)
+; CHECK: define i8* @test1_2(i8* nocapture readnone %x1_2, i8* returned %y1_2)
define i8* @test1_2(i8* %x1_2, i8* %y1_2) {
call void @test1_1(i8* %x1_2, i8* %y1_2)
store i32* null, i32** @g
@@ -168,7 +168,7 @@ define void @test4_1(i8* %x4_1) {
ret void
}
-; CHECK: define i8* @test4_2(i8* nocapture readnone %x4_2, i8* readnone %y4_2, i8* nocapture readnone %z4_2)
+; CHECK: define i8* @test4_2(i8* nocapture readnone %x4_2, i8* readnone returned %y4_2, i8* nocapture readnone %z4_2)
define i8* @test4_2(i8* %x4_2, i8* %y4_2, i8* %z4_2) {
call void @test4_1(i8* null)
store i32* null, i32** @g
Modified: llvm/trunk/test/Transforms/FunctionAttrs/readattrs.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/readattrs.ll?rev=275678&r1=275677&r2=275678&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/FunctionAttrs/readattrs.ll (original)
+++ llvm/trunk/test/Transforms/FunctionAttrs/readattrs.ll Sat Jul 16 02:21:28 2016
@@ -11,7 +11,7 @@ define void @test1_2(i8* %x1_2, i8* %y1_
ret void
}
-; CHECK: define i8* @test2(i8* readnone %p)
+; CHECK: define i8* @test2(i8* readnone returned %p)
define i8* @test2(i8* %p) {
store i32 0, i32* @x
ret i8* %p
@@ -53,7 +53,7 @@ define void @test7_1(i32* inalloca %a) {
ret void
}
-; CHECK: define i32* @test8_1(i32* readnone %p)
+; CHECK: define i32* @test8_1(i32* readnone returned %p)
define i32* @test8_1(i32* %p) {
entry:
ret i32* %p
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