zequanwu updated this revision to Diff 259455.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D78659/new/
https://reviews.llvm.org/D78659
Files:
clang/include/clang/Basic/Attr.td
clang/include/clang/Basic/AttrDocs.td
clang/lib/CodeGen/CGCall.cpp
clang/test/CodeGen/attr-nomerge.c
clang/test/Misc/pragma-attribute-supported-attributes-list.test
llvm/include/llvm/IR/Attributes.td
llvm/include/llvm/IR/InstrTypes.h
llvm/lib/IR/Attributes.cpp
llvm/lib/IR/Verifier.cpp
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
Index: llvm/lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1287,6 +1287,14 @@
if (!TTI.isProfitableToHoist(I1) || !TTI.isProfitableToHoist(I2))
return Changed;
+ // If any of the two call sites has nomerge attribute, stop hoisting.
+ if (const auto *CB1 = dyn_cast<CallBase>(I1))
+ if (CB1->cannotMerge())
+ return Changed;
+ if (const auto *CB2 = dyn_cast<CallBase>(I2))
+ if (CB2->cannotMerge())
+ return Changed;
+
if (isa<DbgInfoIntrinsic>(I1) || isa<DbgInfoIntrinsic>(I2)) {
assert (isa<DbgInfoIntrinsic>(I1) && isa<DbgInfoIntrinsic>(I2));
// The debug location is an integral part of a debug info intrinsic
@@ -1472,8 +1480,9 @@
// Conservatively return false if I is an inline-asm instruction. Sinking
// and merging inline-asm instructions can potentially create arguments
// that cannot satisfy the inline-asm constraints.
+ // If the instruction has nomerge attribute, return false.
if (const auto *C = dyn_cast<CallBase>(I))
- if (C->isInlineAsm())
+ if (C->isInlineAsm() || C->cannotMerge())
return false;
// Each instruction must have zero or one use.
Index: llvm/lib/IR/Verifier.cpp
===================================================================
--- llvm/lib/IR/Verifier.cpp
+++ llvm/lib/IR/Verifier.cpp
@@ -1509,6 +1509,7 @@
/// Return true if this attribute kind only applies to functions.
static bool isFuncOnlyAttr(Attribute::AttrKind Kind) {
switch (Kind) {
+ case Attribute::NoMerge:
case Attribute::NoReturn:
case Attribute::NoSync:
case Attribute::WillReturn:
Index: llvm/lib/IR/Attributes.cpp
===================================================================
--- llvm/lib/IR/Attributes.cpp
+++ llvm/lib/IR/Attributes.cpp
@@ -368,6 +368,8 @@
return "noinline";
if (hasAttribute(Attribute::NonLazyBind))
return "nonlazybind";
+ if (hasAttribute(Attribute::NoMerge))
+ return "nomerge";
if (hasAttribute(Attribute::NonNull))
return "nonnull";
if (hasAttribute(Attribute::NoRedZone))
Index: llvm/include/llvm/IR/InstrTypes.h
===================================================================
--- llvm/include/llvm/IR/InstrTypes.h
+++ llvm/include/llvm/IR/InstrTypes.h
@@ -1717,6 +1717,9 @@
addAttribute(AttributeList::FunctionIndex, Attribute::NoDuplicate);
}
+ /// Determine if the invoke cannot be tail merged.
+ bool cannotMerge() const { return hasFnAttr(Attribute::NoMerge); }
+
/// Determine if the invoke is convergent
bool isConvergent() const { return hasFnAttr(Attribute::Convergent); }
void setConvergent() {
Index: llvm/include/llvm/IR/Attributes.td
===================================================================
--- llvm/include/llvm/IR/Attributes.td
+++ llvm/include/llvm/IR/Attributes.td
@@ -97,6 +97,9 @@
/// Function is called early and/or often, so lazy binding isn't worthwhile.
def NonLazyBind : EnumAttr<"nonlazybind">;
+/// Disable tail merge for this function
+def NoMerge : EnumAttr<"nomerge">;
+
/// Pointer is known to be not null.
def NonNull : EnumAttr<"nonnull">;
Index: clang/test/Misc/pragma-attribute-supported-attributes-list.test
===================================================================
--- clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -88,6 +88,7 @@
// CHECK-NEXT: NoEscape (SubjectMatchRule_variable_is_parameter)
// CHECK-NEXT: NoInline (SubjectMatchRule_function)
// CHECK-NEXT: NoInstrumentFunction (SubjectMatchRule_function)
+// CHECK-NEXT: NoMerge (SubjectMatchRule_function)
// CHECK-NEXT: NoMicroMips (SubjectMatchRule_function)
// CHECK-NEXT: NoMips16 (SubjectMatchRule_function)
// CHECK-NEXT: NoSanitize (SubjectMatchRule_function, SubjectMatchRule_objc_method, SubjectMatchRule_variable_is_global)
Index: clang/test/CodeGen/attr-nomerge.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/attr-nomerge.c
@@ -0,0 +1,16 @@
+// RUN: %clang_cc1 -O2 -S -emit-llvm %s -o - | FileCheck %s
+
+void bar() __attribute__((nomerge));
+
+void foo(int i) {
+ if (i == 5) {
+ bar();
+ }
+ else if (i == 7) {
+ bar();
+ }
+ bar();
+}
+// CHECK: tail call void
+// CHECK: tail call void
+// CHECK: tail call void
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -1905,6 +1905,8 @@
FuncAttrs.addAttribute(llvm::Attribute::NoDuplicate);
if (TargetDecl->hasAttr<ConvergentAttr>())
FuncAttrs.addAttribute(llvm::Attribute::Convergent);
+ if (TargetDecl->hasAttr<NoMergeAttr>())
+ FuncAttrs.addAttribute(llvm::Attribute::NoMerge);
if (const FunctionDecl *Fn = dyn_cast<FunctionDecl>(TargetDecl)) {
AddAttributesFromFunctionProtoType(
Index: clang/include/clang/Basic/AttrDocs.td
===================================================================
--- clang/include/clang/Basic/AttrDocs.td
+++ clang/include/clang/Basic/AttrDocs.td
@@ -350,6 +350,14 @@
}];
}
+def NoMergeDocs : Documentation {
+ let Category = DocCatFunction;
+ let Content = [{
+A function declared as ``nomerge`` shall not be tail merged at call sites during
+optimization phase.
+ }];
+}
+
def AssertCapabilityDocs : Documentation {
let Category = DocCatFunction;
let Heading = "assert_capability, assert_shared_capability";
Index: clang/include/clang/Basic/Attr.td
===================================================================
--- clang/include/clang/Basic/Attr.td
+++ clang/include/clang/Basic/Attr.td
@@ -1793,6 +1793,13 @@
let Documentation = [Undocumented];
}
+def NoMerge : InheritableAttr {
+ let Spellings = [Clang<"nomerge">];
+ let Subjects = SubjectList<[Function]>;
+ let Documentation = [NoMergeDocs];
+ let SimpleHandler = 1;
+}
+
def NoInstrumentFunction : InheritableAttr {
let Spellings = [GCC<"no_instrument_function">];
let Subjects = SubjectList<[Function]>;
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