[llvm] 6c742fd - [Attributor] Deduce dereferenceable based on accessed bytes map
Hideto Ueno via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 28 22:59:27 PST 2019
Author: Hideto Ueno
Date: 2019-11-29T06:55:58Z
New Revision: 6c742fdbf48ee3ae9afb2ab1568397a3b89276e5
URL: https://github.com/llvm/llvm-project/commit/6c742fdbf48ee3ae9afb2ab1568397a3b89276e5
DIFF: https://github.com/llvm/llvm-project/commit/6c742fdbf48ee3ae9afb2ab1568397a3b89276e5.diff
LOG: [Attributor] Deduce dereferenceable based on accessed bytes map
Summary:
This patch introduces the deduction based on load/store instructions whose pointer operand is a non-inbounds GEP instruction.
For example if we have,
```
void f(int *u){
u[0] = 0;
u[1] = 1;
u[2] = 2;
}
```
then u must be dereferenceable(12).
This patch is inspired by D64258
Reviewers: jdoerfert, spatel, hfinkel, RKSimon, sstefan1, xbolva00, dtemirbulatov
Reviewed By: jdoerfert
Subscribers: jfb, lebedev.ri, xbolva00, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70714
Added:
Modified:
llvm/include/llvm/Transforms/IPO/Attributor.h
llvm/lib/Transforms/IPO/Attributor.cpp
llvm/test/Transforms/InferFunctionAttrs/dereferenceable.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
index a75a047b7fd0..4f6f823a230b 100644
--- a/llvm/include/llvm/Transforms/IPO/Attributor.h
+++ b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -1820,6 +1820,42 @@ struct DerefState : AbstractState {
/// State representing for dereferenceable bytes.
IncIntegerState<> DerefBytesState;
+ /// Map representing for accessed memory offsets and sizes.
+ /// A key is Offset and a value is size.
+ /// If there is a load/store instruction something like,
+ /// p[offset] = v;
+ /// (offset, sizeof(v)) will be inserted to this map.
+ /// std::map is used because we want to iterate keys in ascending order.
+ std::map<int64_t, uint64_t> AccessedBytesMap;
+
+ /// Helper function to calculate dereferenceable bytes from current known
+ /// bytes and accessed bytes.
+ ///
+ /// int f(int *A){
+ /// *A = 0;
+ /// *(A+2) = 2;
+ /// *(A+1) = 1;
+ /// *(A+10) = 10;
+ /// }
+ /// ```
+ /// In that case, AccessedBytesMap is `{0:4, 4:4, 8:4, 40:4}`.
+ /// AccessedBytesMap is std::map so it is iterated in accending order on
+ /// key(Offset). So KnownBytes will be updated like this: |Access | KnownBytes
+ /// |(0, 4)| 0 -> 4
+ /// |(4, 4)| 4 -> 8
+ /// |(8, 4)| 8 -> 12
+ /// |(40, 4) | 12 (break)
+ void computeKnownDerefBytesFromAccessedMap() {
+ int64_t KnownBytes = DerefBytesState.getKnown();
+ for (auto &Access : AccessedBytesMap) {
+ if (KnownBytes < Access.first)
+ break;
+ KnownBytes = std::max(KnownBytes, Access.first + (int64_t)Access.second);
+ }
+
+ DerefBytesState.takeKnownMaximum(KnownBytes);
+ }
+
/// State representing that whether the value is globaly dereferenceable.
BooleanState GlobalState;
@@ -1849,6 +1885,9 @@ struct DerefState : AbstractState {
/// Update known dereferenceable bytes.
void takeKnownDerefBytesMaximum(uint64_t Bytes) {
DerefBytesState.takeKnownMaximum(Bytes);
+
+ // Known bytes might increase.
+ computeKnownDerefBytesFromAccessedMap();
}
/// Update assumed dereferenceable bytes.
@@ -1856,6 +1895,14 @@ struct DerefState : AbstractState {
DerefBytesState.takeAssumedMinimum(Bytes);
}
+ /// Add accessed bytes to the map.
+ void addAccessedBytes(int64_t Offset, uint64_t Size) {
+ AccessedBytesMap[Offset] = std::max(AccessedBytesMap[Offset], Size);
+
+ // Known bytes might increase.
+ computeKnownDerefBytesFromAccessedMap();
+ }
+
/// Equality for DerefState.
bool operator==(const DerefState &R) {
return this->DerefBytesState == R.DerefBytesState &&
diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index e73698620de6..48da7e7bdd03 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -2961,12 +2961,34 @@ struct AADereferenceableImpl : AADereferenceable {
const StateType &getState() const override { return *this; }
/// }
+ /// Helper function for collecting accessed bytes in must-be-executed-context
+ void addAccessedBytesForUse(Attributor &A, const Use *U,
+ const Instruction *I) {
+ const Value *UseV = U->get();
+ if (!UseV->getType()->isPointerTy())
+ return;
+
+ Type *PtrTy = UseV->getType();
+ const DataLayout &DL = A.getDataLayout();
+ int64_t Offset;
+ if (const Value *Base = getBasePointerOfAccessPointerOperand(
+ I, Offset, DL, /*AllowNonInbounds*/ true)) {
+ if (Base == &getAssociatedValue() && getPointerOperand(I) == UseV) {
+ uint64_t Size = DL.getTypeStoreSize(PtrTy->getPointerElementType());
+ addAccessedBytes(Offset, Size);
+ }
+ }
+ return;
+ }
+
/// See AAFromMustBeExecutedContext
bool followUse(Attributor &A, const Use *U, const Instruction *I) {
bool IsNonNull = false;
bool TrackUse = false;
int64_t DerefBytes = getKnownNonNullAndDerefBytesForUse(
A, *this, getAssociatedValue(), U, I, IsNonNull, TrackUse);
+
+ addAccessedBytesForUse(A, U, I);
takeKnownDerefBytesMaximum(DerefBytes);
return TrackUse;
}
diff --git a/llvm/test/Transforms/InferFunctionAttrs/dereferenceable.ll b/llvm/test/Transforms/InferFunctionAttrs/dereferenceable.ll
index bf7daba40d43..b6b699fac85e 100644
--- a/llvm/test/Transforms/InferFunctionAttrs/dereferenceable.ll
+++ b/llvm/test/Transforms/InferFunctionAttrs/dereferenceable.ll
@@ -48,8 +48,7 @@ define double @PR21780_only_access3_without_inbounds(double* %ptr) {
define double @PR21780_without_inbounds(double* %ptr) {
; CHECK-LABEL: @PR21780_without_inbounds(double* %ptr)
-; FIXME: this should be @PR21780_without_inbounds(double* nonnull dereferenceable(32) %ptr)
-; ATTRIBUTOR-LABEL: @PR21780_without_inbounds(double* nocapture nofree nonnull readonly align 8 dereferenceable(8) %ptr)
+; ATTRIBUTOR-LABEL: @PR21780_without_inbounds(double* nocapture nofree nonnull readonly align 8 dereferenceable(32) %ptr)
%arrayidx1 = getelementptr double, double* %ptr, i64 1
%arrayidx2 = getelementptr double, double* %ptr, i64 2
@@ -67,6 +66,7 @@ define double @PR21780_without_inbounds(double* %ptr) {
define void @gep0(i8* %unused, i8* %other, i8* %ptr) {
; CHECK-LABEL: @gep0(i8* %unused, i8* %other, i8* %ptr)
+; ATTRIBUTOR-LABEL: @gep0(i8* nocapture nofree readnone %unused, i8* nocapture nofree nonnull writeonly dereferenceable(1) %other, i8* nocapture nofree nonnull readonly dereferenceable(3) %ptr)
%arrayidx0 = getelementptr i8, i8* %ptr, i64 0
%arrayidx1 = getelementptr i8, i8* %ptr, i64 1
%arrayidx2 = getelementptr i8, i8* %ptr, i64 2
@@ -82,6 +82,7 @@ define void @gep0(i8* %unused, i8* %other, i8* %ptr) {
define void @ordering(i8* %ptr1, i32* %ptr2) {
; CHECK-LABEL: @ordering(i8* %ptr1, i32* %ptr2)
+; ATTRIBUTOR-LABEL: @ordering(i8* nocapture nofree nonnull readonly dereferenceable(3) %ptr1, i32* nocapture nofree nonnull readonly dereferenceable(8) %ptr2)
%a20 = getelementptr i32, i32* %ptr2, i64 0
%a12 = getelementptr i8, i8* %ptr1, i64 2
%t12 = load i8, i8* %a12
@@ -99,6 +100,7 @@ define void @ordering(i8* %ptr1, i32* %ptr2) {
define void @not_entry_but_guaranteed_to_execute(i8* %ptr) {
; CHECK-LABEL: @not_entry_but_guaranteed_to_execute(i8* %ptr)
+; ATTRIBUTOR-LABEL: @not_entry_but_guaranteed_to_execute(i8* nocapture nofree nonnull readonly dereferenceable(3) %ptr)
entry:
br label %exit
exit:
@@ -115,6 +117,7 @@ exit:
define void @not_entry_not_guaranteed_to_execute(i8* %ptr, i1 %cond) {
; CHECK-LABEL: @not_entry_not_guaranteed_to_execute(i8* %ptr, i1 %cond)
+; ATTRIBUTOR-LABEL: @not_entry_not_guaranteed_to_execute(i8* nocapture nofree readonly %ptr, i1 %cond)
entry:
br i1 %cond, label %loads, label %exit
loads:
@@ -133,6 +136,7 @@ exit:
define void @partial_in_entry(i16* %ptr, i1 %cond) {
; CHECK-LABEL: @partial_in_entry(i16* %ptr, i1 %cond)
+; ATTRIBUTOR-LABEL: @partial_in_entry(i16* nocapture nofree nonnull readonly dereferenceable(4) %ptr, i1 %cond)
entry:
%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
@@ -152,6 +156,7 @@ exit:
define void @volatile_is_not_dereferenceable(i16* %ptr) {
; CHECK-LABEL: @volatile_is_not_dereferenceable(i16* %ptr)
+; ATTRIBUTOR-LABEL: @volatile_is_not_dereferenceable(i16* nofree %ptr)
%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
@@ -165,6 +170,7 @@ define void @volatile_is_not_dereferenceable(i16* %ptr) {
define void @atomic_is_alright(i16* %ptr) {
; CHECK-LABEL: @atomic_is_alright(i16* %ptr)
+; ATTRIBUTOR-LABEL: @atomic_is_alright(i16* nocapture nofree nonnull readonly align 2 dereferenceable(6) %ptr)
%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
@@ -178,6 +184,7 @@ declare void @may_not_return()
define void @not_guaranteed_to_transfer_execution(i16* %ptr) {
; CHECK-LABEL: @not_guaranteed_to_transfer_execution(i16* %ptr)
+; ATTRIBUTOR-LABEL: @not_guaranteed_to_transfer_execution(i16* nocapture nonnull readonly dereferenceable(2) %ptr)
%arrayidx0 = getelementptr i16, i16* %ptr, i64 0
%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
@@ -192,6 +199,7 @@ define void @not_guaranteed_to_transfer_execution(i16* %ptr) {
define void @variable_gep_index(i8* %unused, i8* %ptr, i64 %variable_index) {
; CHECK-LABEL: @variable_gep_index(i8* %unused, i8* %ptr, i64 %variable_index)
+; ATTRIBUTOR-LABEL: @variable_gep_index(i8* nocapture nofree readnone %unused, i8* nocapture nofree nonnull readonly dereferenceable(1) %ptr, i64 %variable_index)
%arrayidx1 = getelementptr i8, i8* %ptr, i64 %variable_index
%arrayidx2 = getelementptr i8, i8* %ptr, i64 2
%t0 = load i8, i8* %ptr
@@ -204,6 +212,8 @@ define void @variable_gep_index(i8* %unused, i8* %ptr, i64 %variable_index) {
define void @multi_index_gep(<4 x i8>* %ptr) {
; CHECK-LABEL: @multi_index_gep(<4 x i8>* %ptr)
+; FIXME: %ptr should be dereferenceable(4)
+; ATTRIBUTOR-LABEL: @multi_index_gep(<4 x i8>* nocapture nofree nonnull readonly dereferenceable(1) %ptr)
%arrayidx00 = getelementptr <4 x i8>, <4 x i8>* %ptr, i64 0, i64 0
%t0 = load i8, i8* %arrayidx00
ret void
@@ -213,6 +223,7 @@ define void @multi_index_gep(<4 x i8>* %ptr) {
define void @not_byte_multiple(i9* %ptr) {
; CHECK-LABEL: @not_byte_multiple(i9* %ptr)
+; ATTRIBUTOR-LABEL: @not_byte_multiple(i9* nocapture nofree nonnull readonly dereferenceable(2) %ptr)
%arrayidx0 = getelementptr i9, i9* %ptr, i64 0
%t0 = load i9, i9* %arrayidx0
ret void
@@ -222,6 +233,7 @@ define void @not_byte_multiple(i9* %ptr) {
define void @no_pointer_deref(i16* %ptr) {
; CHECK-LABEL: @no_pointer_deref(i16* %ptr)
+; ATTRIBUTOR-LABEL: @no_pointer_deref(i16* nocapture nofree readonly %ptr)
%arrayidx1 = getelementptr i16, i16* %ptr, i64 1
%arrayidx2 = getelementptr i16, i16* %ptr, i64 2
%t1 = load i16, i16* %arrayidx1
@@ -233,6 +245,7 @@ define void @no_pointer_deref(i16* %ptr) {
define void @non_consecutive(i32* %ptr) {
; CHECK-LABEL: @non_consecutive(i32* %ptr)
+; ATTRIBUTOR-LABEL: @non_consecutive(i32* nocapture nofree nonnull readonly dereferenceable(8) %ptr)
%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
@@ -246,6 +259,7 @@ define void @non_consecutive(i32* %ptr) {
define void @more_bytes(i32* dereferenceable(8) %ptr) {
; CHECK-LABEL: @more_bytes(i32* dereferenceable(8) %ptr)
+; ATTRIBUTOR-LABEL: @more_bytes(i32* nocapture nofree nonnull readonly dereferenceable(16) %ptr)
%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
@@ -261,6 +275,7 @@ define void @more_bytes(i32* dereferenceable(8) %ptr) {
define void @more_bytes_and_not_null(i32* dereferenceable_or_null(8) %ptr) {
; CHECK-LABEL: @more_bytes_and_not_null(i32* dereferenceable_or_null(8) %ptr)
+; ATTRIBUTOR-LABEL: @more_bytes_and_not_null(i32* nocapture nofree nonnull readonly dereferenceable(16) %ptr)
%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
@@ -276,6 +291,7 @@ define void @more_bytes_and_not_null(i32* dereferenceable_or_null(8) %ptr) {
define void @better_bytes(i32* dereferenceable(100) %ptr) {
; CHECK-LABEL: @better_bytes(i32* dereferenceable(100) %ptr)
+; ATTRIBUTOR-LABEL: @better_bytes(i32* nocapture nofree nonnull readonly dereferenceable(100) %ptr)
%arrayidx3 = getelementptr i32, i32* %ptr, i64 3
%arrayidx1 = getelementptr i32, i32* %ptr, i64 1
%arrayidx0 = getelementptr i32, i32* %ptr, i64 0
@@ -289,6 +305,7 @@ define void @better_bytes(i32* dereferenceable(100) %ptr) {
define void @bitcast(i32* %arg) {
; CHECK-LABEL: @bitcast(i32* %arg)
+; ATTRIBUTOR-LABEL: @bitcast(i32* nocapture nofree nonnull readonly dereferenceable(8) %arg)
%ptr = bitcast i32* %arg to float*
%arrayidx0 = getelementptr float, float* %ptr, i64 0
%arrayidx1 = getelementptr float, float* %ptr, i64 1
@@ -299,6 +316,7 @@ define void @bitcast(i32* %arg) {
define void @bitcast_
diff erent_sizes(double* %arg1, i8* %arg2) {
; CHECK-LABEL: @bitcast_
diff erent_sizes(double* %arg1, i8* %arg2)
+; ATTRIBUTOR-LABEL: @bitcast_
diff erent_sizes(double* nocapture nofree nonnull readonly dereferenceable(12) %arg1, i8* nocapture nofree nonnull readonly dereferenceable(16) %arg2)
%ptr1 = bitcast double* %arg1 to float*
%a10 = getelementptr float, float* %ptr1, i64 0
%a11 = getelementptr float, float* %ptr1, i64 1
@@ -317,6 +335,7 @@ define void @bitcast_
diff erent_sizes(double* %arg1, i8* %arg2) {
define void @negative_offset(i32* %arg) {
; CHECK-LABEL: @negative_offset(i32* %arg)
+; ATTRIBUTOR-LABEL: @negative_offset(i32* nocapture nofree nonnull readonly dereferenceable(4) %arg)
%ptr = bitcast i32* %arg to float*
%arrayidx0 = getelementptr float, float* %ptr, i64 0
%arrayidx1 = getelementptr float, float* %ptr, i64 -1
@@ -327,6 +346,7 @@ define void @negative_offset(i32* %arg) {
define void @stores(i32* %arg) {
; CHECK-LABEL: @stores(i32* %arg)
+; ATTRIBUTOR-LABEL: @stores(i32* nocapture nofree nonnull writeonly dereferenceable(8) %arg)
%ptr = bitcast i32* %arg to float*
%arrayidx0 = getelementptr float, float* %ptr, i64 0
%arrayidx1 = getelementptr float, float* %ptr, i64 1
@@ -337,6 +357,7 @@ define void @stores(i32* %arg) {
define void @load_store(i32* %arg) {
; CHECK-LABEL: @load_store(i32* %arg)
+; ATTRIBUTOR-LABEL: @load_store(i32* nocapture nofree nonnull dereferenceable(8) %arg)
%ptr = bitcast i32* %arg to float*
%arrayidx0 = getelementptr float, float* %ptr, i64 0
%arrayidx1 = getelementptr float, float* %ptr, i64 1
@@ -344,3 +365,21 @@ define void @load_store(i32* %arg) {
store float 2.0, float* %arrayidx1
ret void
}
+
+define void @
diff erent_size1(i32* %arg) {
+; CHECK-LABEL: @
diff erent_size1(i32* %arg)
+; ATTRIBUTOR-LABEL: @
diff erent_size1(i32* nocapture nofree nonnull writeonly dereferenceable(8) %arg)
+ %arg-cast = bitcast i32* %arg to double*
+ store double 0.000000e+00, double* %arg-cast
+ store i32 0, i32* %arg
+ ret void
+}
+
+define void @
diff erent_size2(i32* %arg) {
+; CHECK-LABEL: @
diff erent_size2(i32* %arg)
+; ATTRIBUTOR-LABEL: @
diff erent_size2(i32* nocapture nofree nonnull writeonly dereferenceable(8) %arg)
+ store i32 0, i32* %arg
+ %arg-cast = bitcast i32* %arg to double*
+ store double 0.000000e+00, double* %arg-cast
+ ret void
+}
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