[llvm] 0741dec - [Attributor][FIX] Handle droppable uses when replacing values
Johannes Doerfert via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 15 22:57:50 PDT 2020
Author: Johannes Doerfert
Date: 2020-04-16T00:56:08-05:00
New Revision: 0741dec27b049111094aec22f547651bb42a27ce
URL: https://github.com/llvm/llvm-project/commit/0741dec27b049111094aec22f547651bb42a27ce
DIFF: https://github.com/llvm/llvm-project/commit/0741dec27b049111094aec22f547651bb42a27ce.diff
LOG: [Attributor][FIX] Handle droppable uses when replacing values
Since we use the fact that some uses are droppable in the Attributor we
need to handle them explicitly when we replace uses. As an example, an
assumed dead value can have live droppable users. In those we cannot
replace the value simply by an undef. Instead, we either drop the uses
(via `dropDroppableUses`) or keep them as they are. In this patch we do
both, depending on the situation. For values that are dead but not
necessarily removed we keep droppable uses around because they contain
information we might be able to use later. For values that are removed
we drop droppable uses explicitly to avoid replacement with undef.
Added:
Modified:
llvm/include/llvm/Transforms/IPO/Attributor.h
llvm/lib/Transforms/IPO/Attributor.cpp
llvm/lib/Transforms/IPO/AttributorAttributes.cpp
llvm/test/Transforms/Attributor/dereferenceable-1.ll
llvm/test/Transforms/Attributor/nonnull.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
index cc4390f41d49..a4b0c6a605e7 100644
--- a/llvm/include/llvm/Transforms/IPO/Attributor.h
+++ b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -875,11 +875,14 @@ struct Attributor {
}
/// Helper function to replace all uses of \p V with \p NV. Return true if
- /// there is any change.
- bool changeValueAfterManifest(Value &V, Value &NV) {
+ /// there is any change. The flag \p ChangeDroppable indicates if dropppable
+ /// uses should be changed too.
+ bool changeValueAfterManifest(Value &V, Value &NV,
+ bool ChangeDroppable = true) {
bool Changed = false;
for (auto &U : V.uses())
- Changed |= changeUseAfterManifest(U, NV);
+ if (ChangeDroppable || !U.getUser()->isDroppable())
+ Changed |= changeUseAfterManifest(U, NV);
return Changed;
}
diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 4cf2812d0dcc..e8e8aed8d31b 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -1169,6 +1169,7 @@ ChangeStatus Attributor::run() {
for (auto &V : ToBeDeletedInsts) {
if (Instruction *I = dyn_cast_or_null<Instruction>(V)) {
+ I->dropDroppableUses();
CGModifiedFunctions.insert(I->getFunction());
if (!I->getType()->isVoidTy())
I->replaceAllUsesWith(UndefValue::get(I->getType()));
diff --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index be54fb3eb536..21cb9ed9d9aa 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -2675,8 +2675,11 @@ struct AAIsDeadFloating : public AAIsDeadValueImpl {
if (C.hasValue() && C.getValue())
return ChangeStatus::UNCHANGED;
+ // Replace the value with undef as it is dead but keep droppable uses around
+ // as they provide information we don't want to give up on just yet.
UndefValue &UV = *UndefValue::get(V.getType());
- bool AnyChange = A.changeValueAfterManifest(V, UV);
+ bool AnyChange =
+ A.changeValueAfterManifest(V, UV, /* ChangeDropppable */ false);
return AnyChange ? ChangeStatus::CHANGED : ChangeStatus::UNCHANGED;
}
@@ -2703,8 +2706,10 @@ struct AAIsDeadArgument : public AAIsDeadFloating {
if (A.registerFunctionSignatureRewrite(
Arg, /* ReplacementTypes */ {},
Attributor::ArgumentReplacementInfo::CalleeRepairCBTy{},
- Attributor::ArgumentReplacementInfo::ACSRepairCBTy{}))
+ Attributor::ArgumentReplacementInfo::ACSRepairCBTy{})) {
+ Arg.dropDroppableUses();
return ChangeStatus::CHANGED;
+ }
return Changed;
}
diff --git a/llvm/test/Transforms/Attributor/dereferenceable-1.ll b/llvm/test/Transforms/Attributor/dereferenceable-1.ll
index a1da5fbe2d7c..9036667630eb 100644
--- a/llvm/test/Transforms/Attributor/dereferenceable-1.ll
+++ b/llvm/test/Transforms/Attributor/dereferenceable-1.ll
@@ -623,19 +623,19 @@ define void @nonnull_assume_pos(i8* %arg1, i8* %arg2, i8* %arg3, i8* %arg4) {
;
; IS__TUNIT_OPM-LABEL: define {{[^@]+}}@nonnull_assume_pos
; IS__TUNIT_OPM-SAME: (i8* nocapture nofree nonnull readnone dereferenceable(101) [[ARG1:%.*]], i8* nocapture nofree readnone dereferenceable_or_null(31) [[ARG2:%.*]], i8* nocapture nofree nonnull readnone [[ARG3:%.*]], i8* nocapture nofree readnone dereferenceable_or_null(42) [[ARG4:%.*]])
-; IS__TUNIT_OPM-NEXT: call void @llvm.assume(i1 true) #6 [ "nonnull"(i8* undef), "dereferenceable"(i8* undef, i64 1), "dereferenceable"(i8* undef, i64 2), "dereferenceable"(i8* undef, i64 101), "dereferenceable_or_null"(i8* undef, i64 31), "dereferenceable_or_null"(i8* undef, i64 42) ]
+; IS__TUNIT_OPM-NEXT: call void @llvm.assume(i1 true) #6 [ "nonnull"(i8* [[ARG3]]), "dereferenceable"(i8* [[ARG1]], i64 1), "dereferenceable"(i8* [[ARG1]], i64 2), "dereferenceable"(i8* [[ARG1]], i64 101), "dereferenceable_or_null"(i8* [[ARG2]], i64 31), "dereferenceable_or_null"(i8* [[ARG4]], i64 42) ]
; IS__TUNIT_OPM-NEXT: call void @unknown()
; IS__TUNIT_OPM-NEXT: ret void
;
; IS________NPM-LABEL: define {{[^@]+}}@nonnull_assume_pos
; IS________NPM-SAME: (i8* nocapture nofree nonnull readnone dereferenceable(101) [[ARG1:%.*]], i8* nocapture nofree readnone dereferenceable_or_null(31) [[ARG2:%.*]], i8* nocapture nofree nonnull readnone [[ARG3:%.*]], i8* nocapture nofree readnone dereferenceable_or_null(42) [[ARG4:%.*]])
-; IS________NPM-NEXT: call void @llvm.assume(i1 true) #7 [ "nonnull"(i8* undef), "dereferenceable"(i8* undef, i64 1), "dereferenceable"(i8* undef, i64 2), "dereferenceable"(i8* undef, i64 101), "dereferenceable_or_null"(i8* undef, i64 31), "dereferenceable_or_null"(i8* undef, i64 42) ]
+; IS________NPM-NEXT: call void @llvm.assume(i1 true) #7 [ "nonnull"(i8* [[ARG3]]), "dereferenceable"(i8* [[ARG1]], i64 1), "dereferenceable"(i8* [[ARG1]], i64 2), "dereferenceable"(i8* [[ARG1]], i64 101), "dereferenceable_or_null"(i8* [[ARG2]], i64 31), "dereferenceable_or_null"(i8* [[ARG4]], i64 42) ]
; IS________NPM-NEXT: call void @unknown()
; IS________NPM-NEXT: ret void
;
; IS__CGSCC_OPM-LABEL: define {{[^@]+}}@nonnull_assume_pos
; IS__CGSCC_OPM-SAME: (i8* nocapture nofree nonnull readnone dereferenceable(101) [[ARG1:%.*]], i8* nocapture nofree readnone dereferenceable_or_null(31) [[ARG2:%.*]], i8* nocapture nofree nonnull readnone [[ARG3:%.*]], i8* nocapture nofree readnone dereferenceable_or_null(42) [[ARG4:%.*]])
-; IS__CGSCC_OPM-NEXT: call void @llvm.assume(i1 true) #8 [ "nonnull"(i8* undef), "dereferenceable"(i8* undef, i64 1), "dereferenceable"(i8* undef, i64 2), "dereferenceable"(i8* undef, i64 101), "dereferenceable_or_null"(i8* undef, i64 31), "dereferenceable_or_null"(i8* undef, i64 42) ]
+; IS__CGSCC_OPM-NEXT: call void @llvm.assume(i1 true) #8 [ "nonnull"(i8* [[ARG3]]), "dereferenceable"(i8* [[ARG1]], i64 1), "dereferenceable"(i8* [[ARG1]], i64 2), "dereferenceable"(i8* [[ARG1]], i64 101), "dereferenceable_or_null"(i8* [[ARG2]], i64 31), "dereferenceable_or_null"(i8* [[ARG4]], i64 42) ]
; IS__CGSCC_OPM-NEXT: call void @unknown()
; IS__CGSCC_OPM-NEXT: ret void
;
@@ -653,7 +653,7 @@ define void @nonnull_assume_neg(i8* %arg1, i8* %arg2, i8* %arg3) {
; CHECK-LABEL: define {{[^@]+}}@nonnull_assume_neg
; CHECK-SAME: (i8* nocapture nofree readnone [[ARG1:%.*]], i8* nocapture nofree readnone [[ARG2:%.*]], i8* nocapture nofree readnone [[ARG3:%.*]])
; CHECK-NEXT: call void @unknown()
-; CHECK-NEXT: call void @llvm.assume(i1 true) [ "dereferenceable"(i8* undef, i64 101), "dereferenceable"(i8* undef, i64 -2), "dereferenceable_or_null"(i8* undef, i64 31) ]
+; CHECK-NEXT: call void @llvm.assume(i1 true) [ "dereferenceable"(i8* [[ARG1]], i64 101), "dereferenceable"(i8* [[ARG2]], i64 -2), "dereferenceable_or_null"(i8* [[ARG3]], i64 31) ]
; CHECK-NEXT: ret void
;
call void @unknown()
diff --git a/llvm/test/Transforms/Attributor/nonnull.ll b/llvm/test/Transforms/Attributor/nonnull.ll
index e0bdd5155ab1..ce8626ab5943 100644
--- a/llvm/test/Transforms/Attributor/nonnull.ll
+++ b/llvm/test/Transforms/Attributor/nonnull.ll
@@ -185,7 +185,7 @@ declare void @llvm.assume(i1)
define i8* @test10(i8* %a, i64 %n) {
; CHECK-LABEL: define {{[^@]+}}@test10
; CHECK-SAME: (i8* nofree readnone "no-capture-maybe-returned" [[A:%.*]], i64 [[N:%.*]])
-; CHECK-NEXT: call void @llvm.assume(i1 undef)
+; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: [[B:%.*]] = getelementptr inbounds i8, i8* [[A]], i64 [[N]]
; CHECK-NEXT: ret i8* [[B]]
;
More information about the llvm-commits
mailing list