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[BasicAA] Remove special casing of memset_pattern16 in favor of generic attribute inference

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Most of the properties of memset_pattern16 can be now covered by the generic attributes and inferred by InferFunctionAttrs.  The only exceptions are:
- We don't yet have a writeonly attribute for the first argument.
- We don't have an attribute for modeling the access size facts encoded in MemoryLocation.cpp.  

Differential Revision: http://reviews.llvm.org/D15879

llvm-svn: 256911
This commit is contained in:
Philip Reames 2016-01-06 04:53:16 +00:00
parent 23e3fb6f4a
commit 780b59a41c
4 changed files with 35 additions and 13 deletions
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17
lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -543,7 +543,6 @@ static bool isMemsetPattern16(const Function *MS,
isa<IntegerType>(MemsetType->getParamType(2)))
return true;
}
return false;
}
@ -583,9 +582,6 @@ FunctionModRefBehavior BasicAAResult::getModRefBehavior(const Function *F) {
if (F->onlyAccessesArgMemory())
Min = FunctionModRefBehavior(Min & FMRB_OnlyAccessesArgumentPointees);
if (isMemsetPattern16(F, TLI))
Min = FMRB_OnlyAccessesArgumentPointees;
// Otherwise be conservative.
return FunctionModRefBehavior(AAResultBase::getModRefBehavior(F) & Min);
}
@ -609,14 +605,11 @@ ModRefInfo BasicAAResult::getArgModRefInfo(ImmutableCallSite CS,
// We can bound the aliasing properties of memset_pattern16 just as we can
// for memcpy/memset. This is particularly important because the
// LoopIdiomRecognizer likes to turn loops into calls to memset_pattern16
// whenever possible.
if (CS.getCalledFunction() &&
isMemsetPattern16(CS.getCalledFunction(), TLI)) {
assert((ArgIdx == 0 || ArgIdx == 1) &&
"Invalid argument index for memset_pattern16");
return ArgIdx ? MRI_Ref : MRI_Mod;
}
// FIXME: Handle memset_pattern4 and memset_pattern8 also.
// whenever possible. Note that all but the missing writeonly attribute are
// handled via InferFunctionAttr.
if (CS.getCalledFunction() && isMemsetPattern16(CS.getCalledFunction(), TLI))
if (ArgIdx == 0)
return MRI_Mod;
if (CS.paramHasAttr(ArgIdx + 1, Attribute::ReadOnly))
return MRI_Ref;

24
lib/Transforms/IPO/InferFunctionAttrs.cpp
View File

@ -22,6 +22,7 @@ using namespace llvm;
STATISTIC(NumReadNone, "Number of functions inferred as readnone");
STATISTIC(NumReadOnly, "Number of functions inferred as readonly");
STATISTIC(NumArgMemOnly, "Number of functions inferred as argmemonly");
STATISTIC(NumNoUnwind, "Number of functions inferred as nounwind");
STATISTIC(NumNoCapture, "Number of arguments inferred as nocapture");
STATISTIC(NumReadOnlyArg, "Number of arguments inferred as readonly");
@ -44,6 +45,15 @@ static bool setOnlyReadsMemory(Function &F) {
return true;
}
static bool setOnlyAccessesArgMemory(Function &F) {
if (F.onlyAccessesArgMemory())
return false;
F.setOnlyAccessesArgMemory ();
++NumArgMemOnly;
return true;
}
static bool setDoesNotThrow(Function &F) {
if (F.doesNotThrow())
return false;
@ -900,6 +910,20 @@ static bool inferPrototypeAttributes(Function &F,
Changed |= setDoesNotAlias(F, AttributeSet::ReturnIndex);
return Changed;
//TODO: add LibFunc entries for:
//case LibFunc::memset_pattern4:
//case LibFunc::memset_pattern8:
case LibFunc::memset_pattern16:
if (FTy->isVarArg() || FTy->getNumParams() != 3 ||
!isa<PointerType>(FTy->getParamType(0)) ||
!isa<PointerType>(FTy->getParamType(1)) ||
!isa<IntegerType>(FTy->getParamType(2)))
return false;
Changed |= setOnlyAccessesArgMemory(F);
Changed |= setOnlyReadsMemory(F, 2);
return Changed;
default:
// FIXME: It'd be really nice to cover all the library functions we're
// aware of here.

2
test/Analysis/BasicAA/memset_pattern.ll
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@ -18,4 +18,4 @@ entry:
ret i32 %l
}
declare void @memset_pattern16(i8*, i8*, i64)
declare void @memset_pattern16(i8*, i8* readonly, i64) argmemonly

5
test/Transforms/InferFunctionAttrs/annotate.ll
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@ -22,9 +22,14 @@ declare i8* @_Znwj(i64)
declare i8* @_Znwm(i64)
; CHECK: declare noalias nonnull i8* @_Znwm(i64)
declare void @memset_pattern16(i8*, i8*, i64)
; CHECK: declare void @memset_pattern16(i8*, i8*, i64)
; CHECK-POSIX: declare void @memset_pattern16(i8*, i8* readonly, i64) [[G2:#[0-9]+]]
declare i32 @gettimeofday(i8*, i8*)
; CHECK-POSIX: declare i32 @gettimeofday(i8* nocapture, i8* nocapture) [[G0:#[0-9]+]]
; CHECK: attributes [[G0]] = { nounwind }
; CHECK: attributes [[G1]] = { nounwind readonly }
; CHECK-POSIX: attributes [[G0]] = { nounwind }
; CHECK-POSIX: attributes [[G2]] = { argmemonly }