[llvm] r367029 - Revert "[InstCombine] try to narrow a truncated load"
Vlad Tsyrklevich via llvm-commits
llvm-commits at lists.llvm.org
Thu Jul 25 08:37:58 PDT 2019
Author: vlad.tsyrklevich
Date: Thu Jul 25 08:37:57 2019
New Revision: 367029
URL: http://llvm.org/viewvc/llvm-project?rev=367029&view=rev
Log:
Revert "[InstCombine] try to narrow a truncated load"
This reverts commit bc4a63fd3c29c1a8ce22891bf34ee4dccfef578c, this is a
speculative revert to fix a number of sanitizer bots (like
sanitizer-x86_64-linux-bootstrap-ubsan) that have started to see stage2
compiler crashes, presumably due to a miscompile.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/trunk/test/Transforms/InstCombine/trunc-load.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp?rev=367029&r1=367028&r2=367029&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp Thu Jul 25 08:37:57 2019
@@ -681,42 +681,6 @@ static Instruction *shrinkInsertElt(Cast
return nullptr;
}
-static Instruction *narrowLoad(TruncInst &Trunc,
- InstCombiner::BuilderTy &Builder,
- const DataLayout &DL) {
- // Check the layout to ensure we are not creating an unsupported operation.
- // TODO: Create a GEP to offset the load?
- if (!DL.isLittleEndian())
- return nullptr;
- unsigned NarrowBitWidth = Trunc.getDestTy()->getPrimitiveSizeInBits();
- if (!DL.isLegalInteger(NarrowBitWidth))
- return nullptr;
-
- // Match a truncated load with no other uses.
- Value *X;
- if (!match(Trunc.getOperand(0), m_OneUse(m_Load(m_Value(X)))))
- return nullptr;
- LoadInst *WideLoad = cast<LoadInst>(Trunc.getOperand(0));
- if (!WideLoad->isSimple())
- return nullptr;
-
- // Don't narrow this load if we would lose information about the
- // dereferenceable range.
- bool CanBeNull;
- uint64_t DerefBits = X->getPointerDereferenceableBytes(DL, CanBeNull) * 8;
- if (DerefBits < WideLoad->getType()->getPrimitiveSizeInBits())
- return nullptr;
-
- // trunc (load X) --> load (bitcast X)
- PointerType *PtrTy = PointerType::get(Trunc.getDestTy(),
- WideLoad->getPointerAddressSpace());
- Value *Bitcast = Builder.CreatePointerCast(X, PtrTy);
- LoadInst *NarrowLoad = new LoadInst(Trunc.getDestTy(), Bitcast);
- NarrowLoad->setAlignment(WideLoad->getAlignment());
- copyMetadataForLoad(*NarrowLoad, *WideLoad);
- return NarrowLoad;
-}
-
Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
if (Instruction *Result = commonCastTransforms(CI))
return Result;
@@ -876,9 +840,6 @@ Instruction *InstCombiner::visitTrunc(Tr
if (Instruction *I = foldVecTruncToExtElt(CI, *this))
return I;
- if (Instruction *NewLoad = narrowLoad(CI, Builder, DL))
- return NewLoad;
-
return nullptr;
}
Modified: llvm/trunk/test/Transforms/InstCombine/trunc-load.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/trunc-load.ll?rev=367029&r1=367028&r2=367029&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/trunc-load.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/trunc-load.ll Thu Jul 25 08:37:57 2019
@@ -29,15 +29,10 @@ define i32 @truncload_small_deref(i64* d
; On little-endian, we can narrow the load without an offset.
define i32 @truncload_deref(i64* dereferenceable(8) %ptr) {
-; LE-LABEL: @truncload_deref(
-; LE-NEXT: [[TMP1:%.*]] = bitcast i64* [[PTR:%.*]] to i32*
-; LE-NEXT: [[R:%.*]] = load i32, i32* [[TMP1]], align 4
-; LE-NEXT: ret i32 [[R]]
-;
-; BE-LABEL: @truncload_deref(
-; BE-NEXT: [[X:%.*]] = load i64, i64* [[PTR:%.*]], align 4
-; BE-NEXT: [[R:%.*]] = trunc i64 [[X]] to i32
-; BE-NEXT: ret i32 [[R]]
+; CHECK-LABEL: @truncload_deref(
+; CHECK-NEXT: [[X:%.*]] = load i64, i64* [[PTR:%.*]], align 4
+; CHECK-NEXT: [[R:%.*]] = trunc i64 [[X]] to i32
+; CHECK-NEXT: ret i32 [[R]]
;
%x = load i64, i64* %ptr
%r = trunc i64 %x to i32
@@ -47,15 +42,10 @@ define i32 @truncload_deref(i64* derefer
; Preserve alignment.
define i16 @truncload_align(i32* dereferenceable(14) %ptr) {
-; LE-LABEL: @truncload_align(
-; LE-NEXT: [[TMP1:%.*]] = bitcast i32* [[PTR:%.*]] to i16*
-; LE-NEXT: [[R:%.*]] = load i16, i16* [[TMP1]], align 16
-; LE-NEXT: ret i16 [[R]]
-;
-; BE-LABEL: @truncload_align(
-; BE-NEXT: [[X:%.*]] = load i32, i32* [[PTR:%.*]], align 16
-; BE-NEXT: [[R:%.*]] = trunc i32 [[X]] to i16
-; BE-NEXT: ret i16 [[R]]
+; CHECK-LABEL: @truncload_align(
+; CHECK-NEXT: [[X:%.*]] = load i32, i32* [[PTR:%.*]], align 16
+; CHECK-NEXT: [[R:%.*]] = trunc i32 [[X]] to i16
+; CHECK-NEXT: ret i16 [[R]]
;
%x = load i32, i32* %ptr, align 16
%r = trunc i32 %x to i16
@@ -108,40 +98,12 @@ define i32 @truncload_volatile(i64* dere
; Preserve address space.
define i32 @truncload_address_space(i64 addrspace(1)* dereferenceable(8) %ptr) {
-; LE-LABEL: @truncload_address_space(
-; LE-NEXT: [[TMP1:%.*]] = bitcast i64 addrspace(1)* [[PTR:%.*]] to i32 addrspace(1)*
-; LE-NEXT: [[R:%.*]] = load i32, i32 addrspace(1)* [[TMP1]], align 4
-; LE-NEXT: ret i32 [[R]]
-;
-; BE-LABEL: @truncload_address_space(
-; BE-NEXT: [[X:%.*]] = load i64, i64 addrspace(1)* [[PTR:%.*]], align 4
-; BE-NEXT: [[R:%.*]] = trunc i64 [[X]] to i32
-; BE-NEXT: ret i32 [[R]]
+; CHECK-LABEL: @truncload_address_space(
+; CHECK-NEXT: [[X:%.*]] = load i64, i64 addrspace(1)* [[PTR:%.*]], align 4
+; CHECK-NEXT: [[R:%.*]] = trunc i64 [[X]] to i32
+; CHECK-NEXT: ret i32 [[R]]
;
%x = load i64, i64 addrspace(1)* %ptr, align 4
%r = trunc i64 %x to i32
ret i32 %r
}
-
-; Most metadata should be transferred to the narrow load.
-; TODO: We lost the range.
-
-define i32 @truncload_metadata(i64* dereferenceable(8) %ptr) {
-; LE-LABEL: @truncload_metadata(
-; LE-NEXT: [[TMP1:%.*]] = bitcast i64* [[PTR:%.*]] to i32*
-; LE-NEXT: [[R:%.*]] = load i32, i32* [[TMP1]], align 4, !invariant.load !0, !nontemporal !1
-; LE-NEXT: ret i32 [[R]]
-;
-; BE-LABEL: @truncload_metadata(
-; BE-NEXT: [[X:%.*]] = load i64, i64* [[PTR:%.*]], align 4, !range !0, !invariant.load !1, !nontemporal !2
-; BE-NEXT: [[R:%.*]] = trunc i64 [[X]] to i32
-; BE-NEXT: ret i32 [[R]]
-;
- %x = load i64, i64* %ptr, align 4, !invariant.load !0, !nontemporal !1, !range !2
- %r = trunc i64 %x to i32
- ret i32 %r
-}
-
-!0 = !{}
-!1 = !{i32 1}
-!2 = !{i64 0, i64 2}
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