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[GVN] Small tweaks to comments, style, and missed vector handling

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Noticed these while doing a final sweep of the code to make sure I hadn't missed anything in my last couple of patches.  The (minor) missed optimization was noticed because of the stylistic fix to avoid an overly specific cast.

llvm-svn: 354412
This commit is contained in:
Philip Reames 2019-02-20 00:31:28 +00:00
parent 88f7218b05
commit 6b9bc58980
2 changed files with 24 additions and 10 deletions
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10
lib/Transforms/Utils/VNCoercion.cpp
View File

@ -36,8 +36,8 @@ bool canCoerceMustAliasedValueToLoad(Value *StoredVal, Type *LoadTy,
// As a special case, allow coercion of memset used to initialize
// an array w/null. Despite non-integral pointers not generally having a
// specific bit pattern, we do assume null is zero.
if (auto *CI = dyn_cast<ConstantInt>(StoredVal))
return CI->isZero();
if (auto *CI = dyn_cast<Constant>(StoredVal))
return CI->isNullValue();
return false;
}
@ -287,9 +287,8 @@ int analyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr,
// If this is memset, we just need to see if the offset is valid in the size
// of the memset..
if (MI->getIntrinsicID() == Intrinsic::memset) {
Value *StoredVal = cast<MemSetInst>(MI)->getValue();
if (DL.isNonIntegralPointerType(LoadTy->getScalarType())) {
auto *CI = dyn_cast<ConstantInt>(StoredVal);
auto *CI = dyn_cast<ConstantInt>(cast<MemSetInst>(MI)->getValue());
if (!CI || !CI->isZero())
return -1;
}
@ -316,7 +315,8 @@ int analyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr,
if (Offset == -1)
return Offset;
// Don't coerce non-integral pointers to integers or vice versa.
// Don't coerce non-integral pointers to integers or vice versa, and the
// memtransfer is implicitly a raw byte code
if (DL.isNonIntegralPointerType(LoadTy->getScalarType()))
// TODO: Can allow nullptrs from constant zeros
return -1;

24
test/Transforms/GVN/non-integral-pointers.ll
View File

@ -139,18 +139,32 @@ define <1 x i8 addrspace(4)*> @neg_forward_store_vload(<1 x i8 addrspace(4)*> ad
ret <1 x i8 addrspace(4)*> %ref
}
; TODO: missed optimization, we can forward the null.
; Nulls have known bit patterns, so we can forward
define i8 addrspace(4)* @forward_store_zero(i8 addrspace(4)* addrspace(4)* %loc) {
; CHECK-LABEL: @forward_store_zero(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[LOC_BC:%.*]] = bitcast i8 addrspace(4)* addrspace(4)* [[LOC:%.*]] to i64 addrspace(4)*
; CHECK-NEXT: store i64 5, i64 addrspace(4)* [[LOC_BC]]
; CHECK-NEXT: [[REF:%.*]] = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* [[LOC]]
; CHECK-NEXT: ret i8 addrspace(4)* [[REF]]
; CHECK-NEXT: store i64 0, i64 addrspace(4)* [[LOC_BC]]
; CHECK-NEXT: ret i8 addrspace(4)* null
;
entry:
%loc.bc = bitcast i8 addrspace(4)* addrspace(4)* %loc to i64 addrspace(4)*
store i64 5, i64 addrspace(4)* %loc.bc
store i64 0, i64 addrspace(4)* %loc.bc
%ref = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* %loc
ret i8 addrspace(4)* %ref
}
; Nulls have known bit patterns, so we can forward
define i8 addrspace(4)* @forward_store_zero2(i8 addrspace(4)* addrspace(4)* %loc) {
; CHECK-LABEL: @forward_store_zero2(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[LOC_BC:%.*]] = bitcast i8 addrspace(4)* addrspace(4)* [[LOC:%.*]] to <2 x i32> addrspace(4)*
; CHECK-NEXT: store <2 x i32> zeroinitializer, <2 x i32> addrspace(4)* [[LOC_BC]]
; CHECK-NEXT: ret i8 addrspace(4)* null
;
entry:
%loc.bc = bitcast i8 addrspace(4)* addrspace(4)* %loc to <2 x i32> addrspace(4)*
store <2 x i32> zeroinitializer, <2 x i32> addrspace(4)* %loc.bc
%ref = load i8 addrspace(4)*, i8 addrspace(4)* addrspace(4)* %loc
ret i8 addrspace(4)* %ref
}