[llvm] 61a85da - [InferAttributes] Materialize all infered attributes for declaration
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 14 14:45:43 PDT 2021
Author: Philip Reames
Date: 2021-04-14T14:45:24-07:00
New Revision: 61a85da88235983da565bda0160367461fa0f382
URL: https://github.com/llvm/llvm-project/commit/61a85da88235983da565bda0160367461fa0f382
DIFF: https://github.com/llvm/llvm-project/commit/61a85da88235983da565bda0160367461fa0f382.diff
LOG: [InferAttributes] Materialize all infered attributes for declaration
We have some cases today where attributes can be inferred from another on access, but the result is not explicitly materialized in IR. This change is a step towards changing that.
Why? Two main reasons:
* Human clarity. It's really confusing trying to figure out why a transform is triggering when the IR doesn't appear to have the required attributes.
* This avoids the need to special case declarations in e.g. functionattrs. Since we can assume the attribute is present, we can work directly from attributes (and only attributes) without also needing to query accessors on Function to avoid missing cases due to unannotated (but infered on use) declarations. (This piece will appear must easier to follow once D100226 also lands.)
Differential Revision: https://reviews.llvm.org/D100400
Added:
Modified:
llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
llvm/test/Other/cgscc-devirt-iteration.ll
llvm/test/Transforms/InferFunctionAttrs/annotate.ll
llvm/test/Transforms/LICM/strlen.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp b/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
index 685f8f7d7a005..5c022f0df6101 100644
--- a/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
@@ -19,6 +19,41 @@ using namespace llvm;
#define DEBUG_TYPE "inferattrs"
+/// If we can infer one attribute from another on the declaration of a
+/// function, explicitly materialize the maximal set for readability in the IR.
+/// Doing this also allows our CGSCC inference to avoid needing to duplicate
+/// this logic on all calls to declarations (as declarations aren't explicitly
+/// visited by CGSCC passes in the new pass manager.)
+static bool inferAttributesFromOthers(Function &F) {
+ // Note: We explicitly check for attributes rather than using cover functions
+ // because some of the cover functions include the logic being implemented.
+
+ bool Changed = false;
+ // readnone + not convergent implies nosync
+ if (!F.hasFnAttribute(Attribute::NoSync) &&
+ F.doesNotAccessMemory() && !F.isConvergent()) {
+ F.setNoSync();
+ Changed = true;
+ }
+
+ // readonly implies nofree
+ if (!F.hasFnAttribute(Attribute::NoFree) && F.onlyReadsMemory()) {
+ F.setDoesNotFreeMemory();
+ Changed = true;
+ }
+
+ // willreturn implies mustprogress
+ if (!F.hasFnAttribute(Attribute::MustProgress) && F.willReturn()) {
+ F.setMustProgress();
+ Changed = true;
+ }
+
+ // TODO: There are a bunch of cases of restrictive memory effects we
+ // can infer by inspecting arguments of argmemonly-ish functions.
+
+ return Changed;
+}
+
static bool inferAllPrototypeAttributes(
Module &M, function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
bool Changed = false;
@@ -26,8 +61,10 @@ static bool inferAllPrototypeAttributes(
for (Function &F : M.functions())
// We only infer things using the prototype and the name; we don't need
// definitions.
- if (F.isDeclaration() && !F.hasOptNone())
+ if (F.isDeclaration() && !F.hasOptNone()) {
Changed |= inferLibFuncAttributes(F, GetTLI(F));
+ Changed |= inferAttributesFromOthers(F);
+ }
return Changed;
}
diff --git a/llvm/test/Other/cgscc-devirt-iteration.ll b/llvm/test/Other/cgscc-devirt-iteration.ll
index 651b7f3b28539..092c624442db0 100644
--- a/llvm/test/Other/cgscc-devirt-iteration.ll
+++ b/llvm/test/Other/cgscc-devirt-iteration.ll
@@ -4,18 +4,18 @@
; devirtualization here with GVN which forwards a store through a load and to
; an indirect call.
;
-; RUN: opt -aa-pipeline=basic-aa -passes='cgscc(function-attrs,function(gvn,instcombine))' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=BEFORE
-; RUN: opt -aa-pipeline=basic-aa -passes='cgscc(devirt<1>(function-attrs,function(gvn,instcombine)))' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=AFTER --check-prefix=AFTER1
-; RUN: opt -aa-pipeline=basic-aa -passes='cgscc(devirt<2>(function-attrs,function(gvn,instcombine)))' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=AFTER --check-prefix=AFTER2
+; RUN: opt -aa-pipeline=basic-aa -passes='module(inferattrs),cgscc(function-attrs,function(gvn,instcombine))' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=BEFORE
+; RUN: opt -aa-pipeline=basic-aa -passes='module(inferattrs),cgscc(devirt<1>(function-attrs,function(gvn,instcombine)))' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=AFTER --check-prefix=AFTER1
+; RUN: opt -aa-pipeline=basic-aa -passes='module(inferattrs),cgscc(devirt<2>(function-attrs,function(gvn,instcombine)))' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=AFTER --check-prefix=AFTER2
;
-; RUN: not --crash opt -abort-on-max-devirt-iterations-reached -aa-pipeline=basic-aa -passes='cgscc(devirt<1>(function-attrs,function(gvn,instcombine)))' -S < %s
-; RUN: opt -abort-on-max-devirt-iterations-reached -aa-pipeline=basic-aa -passes='cgscc(devirt<2>(function-attrs,function(gvn,instcombine)))' -S < %s
+; RUN: not --crash opt -abort-on-max-devirt-iterations-reached -aa-pipeline=basic-aa -passes='module(inferattrs),cgscc(devirt<1>(function-attrs,function(gvn,instcombine)))' -S < %s
+; RUN: opt -abort-on-max-devirt-iterations-reached -aa-pipeline=basic-aa -passes='module(inferattrs),cgscc(devirt<2>(function-attrs,function(gvn,instcombine)))' -S < %s
;
; We also verify that the real O2 pipeline catches these cases.
; RUN: opt -aa-pipeline=basic-aa -passes='default<O2>' -S < %s | FileCheck %s --check-prefix=CHECK --check-prefix=AFTER --check-prefix=AFTER2
declare void @readnone() readnone
-; CHECK: Function Attrs: readnone
+; CHECK: Function Attrs: nofree nosync readnone
; CHECK-NEXT: declare void @readnone()
declare void @unknown()
@@ -51,7 +51,7 @@ entry:
; devirtualize again, and then deduce readnone.
declare void @readnone_with_arg(void ()**) readnone
-; CHECK: Function Attrs: readnone
+; CHECK: Function Attrs: nofree nosync readnone
; CHECK-LABEL: declare void @readnone_with_arg(void ()**)
define void @test2_a(void ()** %ignore) {
diff --git a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
index c71688ba3d158..05cf79b3874be 100644
--- a/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
+++ b/llvm/test/Transforms/InferFunctionAttrs/annotate.ll
@@ -1016,18 +1016,18 @@ declare i64 @write(i32, i8*, i64)
declare void @memset_pattern16(i8*, i8*, i64)
-; CHECK-DAG: attributes [[NOFREE_NOUNWIND_WILLRETURN]] = { nofree nounwind willreturn }
+; CHECK-DAG: attributes [[NOFREE_NOUNWIND_WILLRETURN]] = { nofree nounwind willreturn mustprogress }
; CHECK-DAG: attributes [[NOFREE_NOUNWIND]] = { nofree nounwind }
-; CHECK-DAG: attributes [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { inaccessiblememonly nofree nounwind willreturn }
-; CHECK-DAG: attributes [[NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { nofree nounwind readonly willreturn }
-; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { argmemonly nofree nounwind willreturn }
+; CHECK-DAG: attributes [[INACCESSIBLEMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { inaccessiblememonly nofree nounwind willreturn mustprogress }
+; CHECK-DAG: attributes [[NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { nofree nounwind readonly willreturn mustprogress }
+; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_WILLRETURN]] = { argmemonly nofree nounwind willreturn mustprogress }
; CHECK-DAG: attributes [[NOFREE_NOUNWIND_READONLY]] = { nofree nounwind readonly }
-; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN]] = { inaccessiblemem_or_argmemonly nounwind willreturn }
-; CHECK-DAG: attributes [[NOFREE_WILLRETURN]] = { nofree willreturn }
-; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { argmemonly nofree nounwind readonly willreturn }
+; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGMEMONLY_NOUNWIND_WILLRETURN]] = { inaccessiblemem_or_argmemonly nounwind willreturn mustprogress }
+; CHECK-DAG: attributes [[NOFREE_WILLRETURN]] = { nofree willreturn mustprogress }
+; CHECK-DAG: attributes [[ARGMEMONLY_NOFREE_NOUNWIND_READONLY_WILLRETURN]] = { argmemonly nofree nounwind readonly willreturn mustprogress }
; CHECK-DAG: attributes [[NOFREE]] = { nofree }
-; CHECK-DAG: attributes [[WILLRETURN]] = { willreturn }
-; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGONLY_NOFREE_NOUNWIND_WILLRETURN]] = { inaccessiblemem_or_argmemonly nofree nounwind willreturn }
+; CHECK-DAG: attributes [[WILLRETURN]] = { willreturn mustprogress }
+; CHECK-DAG: attributes [[INACCESSIBLEMEMORARGONLY_NOFREE_NOUNWIND_WILLRETURN]] = { inaccessiblemem_or_argmemonly nofree nounwind willreturn mustprogress }
; CHECK-DARWIN-DAG: attributes [[ARGMEMONLY_NOFREE]] = { argmemonly nofree }
-; CHECK-NVPTX-DAG: attributes [[NOFREE_NOUNWIND_READNONE]] = { nofree nounwind readnone }
+; CHECK-NVPTX-DAG: attributes [[NOFREE_NOUNWIND_READNONE]] = { nofree nosync nounwind readnone }
diff --git a/llvm/test/Transforms/LICM/strlen.ll b/llvm/test/Transforms/LICM/strlen.ll
index 3f54eecafd800..4a45a06f82f75 100644
--- a/llvm/test/Transforms/LICM/strlen.ll
+++ b/llvm/test/Transforms/LICM/strlen.ll
@@ -13,7 +13,7 @@ loop:
}
; CHECK: declare i64 @strlen(i8* nocapture) #0
-; CHECK: attributes #0 = { argmemonly nofree nounwind readonly willreturn }
+; CHECK: attributes #0 = { argmemonly nofree nounwind readonly willreturn mustprogress }
declare i64 @strlen(i8*)
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