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This change helps to prevents mixing fine grained and non fine grained bit-field
addressing schemes, which can result in incorrect poison state at
initialization. The IR function attribute fine_grained_bitfields is only added
when fine grained bitfield accesses are enable. The attribute is used by opt to
prevent inlining.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D129542
Files:
clang/lib/CodeGen/CGCall.cpp
clang/lib/CodeGen/CodeGenFunction.cpp
clang/test/CodeGen/fine-grained-bitfield-accesses.c
Index: clang/test/CodeGen/fine-grained-bitfield-accesses.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/fine-grained-bitfield-accesses.c
@@ -0,0 +1,21 @@
+// RUN: %clang -ffine-grained-bitfield-accesses -S -emit-llvm -o - %s |
FileCheck %s
+// CHECK: define{{.*}} @g(){{.*}} #[[GATTR:[0-9]+]] {
+// CHECK: declare{{.*}} void @f(ptr noundef){{.*}} #[[FATTR:[0-9]+]]
+// CHECK: attributes #[[GATTR]] = {{.*}} fine_grained_bitfields {{.*}}
+// CHECK: attributes #[[FATTR]] = {{.*}} fine_grained_bitfields {{.*}}
+//
+// Verify that the clang fine-grained-bitfield-accesses option adds the IR
+// function attribute fine_grained_bitfields.
+struct X {
+ int a : 8;
+ int b : 24;
+};
+
+void f(struct X*);
+
+int g() {
+ struct X x;
+ x.a = 10;
+ f(&x);
+ return x.a;
+}
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -984,6 +984,11 @@
Fn->addFnAttr(llvm::Attribute::StrictFP);
}
+ // The fine grained bit-fields attribute is used to determine IPO inlining
+ // compatibility.
+ if (getTypes().getCodeGenOpts().FineGrainedBitfieldAccesses)
+ Fn->addFnAttr(llvm::Attribute::FineGrainedBitfields);
+
// If a custom alignment is used, force realigning to this alignment on
// any main function which certainly will need it.
if (FD && ((FD->isMain() || FD->isMSVCRTEntryPoint()) &&
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -1890,6 +1890,9 @@
if (CodeGenOpts.SpeculativeLoadHardening)
FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening);
+ if (getTypes().getCodeGenOpts().FineGrainedBitfieldAccesses)
+ FuncAttrs.addAttribute(llvm::Attribute::FineGrainedBitfields);
+
// Add zero-call-used-regs attribute.
switch (CodeGenOpts.getZeroCallUsedRegs()) {
case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::Skip:
Index: clang/test/CodeGen/fine-grained-bitfield-accesses.c
===================================================================
--- /dev/null
+++ clang/test/CodeGen/fine-grained-bitfield-accesses.c
@@ -0,0 +1,21 @@
+// RUN: %clang -ffine-grained-bitfield-accesses -S -emit-llvm -o - %s | FileCheck %s
+// CHECK: define{{.*}} @g(){{.*}} #[[GATTR:[0-9]+]] {
+// CHECK: declare{{.*}} void @f(ptr noundef){{.*}} #[[FATTR:[0-9]+]]
+// CHECK: attributes #[[GATTR]] = {{.*}} fine_grained_bitfields {{.*}}
+// CHECK: attributes #[[FATTR]] = {{.*}} fine_grained_bitfields {{.*}}
+//
+// Verify that the clang fine-grained-bitfield-accesses option adds the IR
+// function attribute fine_grained_bitfields.
+struct X {
+ int a : 8;
+ int b : 24;
+};
+
+void f(struct X*);
+
+int g() {
+ struct X x;
+ x.a = 10;
+ f(&x);
+ return x.a;
+}
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -984,6 +984,11 @@
Fn->addFnAttr(llvm::Attribute::StrictFP);
}
+ // The fine grained bit-fields attribute is used to determine IPO inlining
+ // compatibility.
+ if (getTypes().getCodeGenOpts().FineGrainedBitfieldAccesses)
+ Fn->addFnAttr(llvm::Attribute::FineGrainedBitfields);
+
// If a custom alignment is used, force realigning to this alignment on
// any main function which certainly will need it.
if (FD && ((FD->isMain() || FD->isMSVCRTEntryPoint()) &&
Index: clang/lib/CodeGen/CGCall.cpp
===================================================================
--- clang/lib/CodeGen/CGCall.cpp
+++ clang/lib/CodeGen/CGCall.cpp
@@ -1890,6 +1890,9 @@
if (CodeGenOpts.SpeculativeLoadHardening)
FuncAttrs.addAttribute(llvm::Attribute::SpeculativeLoadHardening);
+ if (getTypes().getCodeGenOpts().FineGrainedBitfieldAccesses)
+ FuncAttrs.addAttribute(llvm::Attribute::FineGrainedBitfields);
+
// Add zero-call-used-regs attribute.
switch (CodeGenOpts.getZeroCallUsedRegs()) {
case llvm::ZeroCallUsedRegs::ZeroCallUsedRegsKind::Skip:
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