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Add FramePointerKind::NonLeafNoReserve #163775

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2cb9a74
Add FramePointerKind::NonLeafNoReserve
omern1 Oct 16, 2025
20fe190
Fix formatting
omern1 Oct 16, 2025
c6fde3d
Add `-mreserve-frame-pointer-reg`
omern1 Oct 20, 2025
084c704
Fix formatting
omern1 Oct 20, 2025
ff4b02d
Address review comments
omern1 Oct 24, 2025
edd81c6
Fix formatting
omern1 Oct 24, 2025
abe2eb4
Fix test
omern1 Oct 27, 2025
2911c45
Fix MLIR
omern1 Oct 28, 2025
bc9a25f
Merge remote-tracking branch 'upstream/main' into regalloc-fix
omern1 Oct 29, 2025
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2 changes: 1 addition & 1 deletion clang/include/clang/Basic/CodeGenOptions.def
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Expand Up @@ -54,7 +54,7 @@ CODEGENOPT(SeparateNamedSections, 1, 0, Benign) ///< Set for -fseparate-named-se
CODEGENOPT(EnableAIXExtendedAltivecABI, 1, 0, Benign) ///< Set for -mabi=vec-extabi. Enables the extended Altivec ABI on AIX.
CODEGENOPT(XCOFFReadOnlyPointers, 1, 0, Benign) ///< Set for -mxcoff-roptr.
CODEGENOPT(AllTocData, 1, 0, Benign) ///< AIX -mtocdata
ENUM_CODEGENOPT(FramePointer, FramePointerKind, 2, FramePointerKind::None, Benign) /// frame-pointer: all,non-leaf,reserved,none
ENUM_CODEGENOPT(FramePointer, FramePointerKind, 3, FramePointerKind::None, Benign) /// frame-pointer: all,non-leaf,non-leaf-no-reserve,reserved,none

ENUM_CODEGENOPT(ExceptionHandling, ExceptionHandlingKind, 3, ExceptionHandlingKind::None, NotCompatible)

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13 changes: 9 additions & 4 deletions clang/include/clang/Basic/CodeGenOptions.h
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Expand Up @@ -155,10 +155,13 @@ class CodeGenOptions : public CodeGenOptionsBase {
std::string BinutilsVersion;

enum class FramePointerKind {
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Silly question - why is this enum ordered so differently to llvm/include/llvm/Support/CodeGen.h?

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I've checked and the order doesn't appear to matter apart from some sanitizer tests which have the frame pointer metadata written like: !1 = !{i32 7, !"frame-pointer", i32 2}. I can make it consistent if you'd like.

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I've no strong objection to keeping it as it is but it would make sense to match the llvm implementation (assuming that's the one hardwired by metadata) - but I assume that can be done as a followup PR. Thanks for checking

None, // Omit all frame pointers.
Reserved, // Maintain valid frame pointer chain.
NonLeaf, // Keep non-leaf frame pointers.
All, // Keep all frame pointers.
NonLeafNoReserve, // Keep non-leaf frame pointers, allow the FP to be used
// as a GPR in leaf functions.
None, // Omit all frame pointers.
Reserved, // Maintain valid frame pointer chain.
NonLeaf, // Keep non-leaf frame pointers, don't allow the FP to be used as a
// GPR in leaf functions.
All, // Keep all frame pointers.
};

static StringRef getFramePointerKindName(FramePointerKind Kind) {
Expand All @@ -167,6 +170,8 @@ class CodeGenOptions : public CodeGenOptionsBase {
return "none";
case FramePointerKind::Reserved:
return "reserved";
case FramePointerKind::NonLeafNoReserve:
return "non-leaf-no-reserve";
case FramePointerKind::NonLeaf:
return "non-leaf";
case FramePointerKind::All:
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4 changes: 2 additions & 2 deletions clang/include/clang/Driver/Options.td
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Expand Up @@ -8481,8 +8481,8 @@ def pic_is_pie : Flag<["-"], "pic-is-pie">,
MarshallingInfoFlag<LangOpts<"PIE">>;

def mframe_pointer_EQ : Joined<["-"], "mframe-pointer=">,
HelpText<"Specify which frame pointers to retain.">, Values<"all,non-leaf,reserved,none">,
NormalizedValuesScope<"CodeGenOptions::FramePointerKind">, NormalizedValues<["All", "NonLeaf", "Reserved", "None"]>,
HelpText<"Specify which frame pointers to retain.">, Values<"all,non-leaf,non-leaf-no-reserve,reserved,none">,
NormalizedValuesScope<"CodeGenOptions::FramePointerKind">, NormalizedValues<["All", "NonLeaf", "NonLeafNoReserve", "Reserved", "None"]>,
MarshallingInfoEnum<CodeGenOpts<"FramePointer">, "None">;


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1 change: 1 addition & 0 deletions clang/lib/CodeGen/CGCall.cpp
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Expand Up @@ -1990,6 +1990,7 @@ static void getTrivialDefaultFunctionAttributes(
// This is the default behavior.
break;
case CodeGenOptions::FramePointerKind::Reserved:
case CodeGenOptions::FramePointerKind::NonLeafNoReserve:
case CodeGenOptions::FramePointerKind::NonLeaf:
case CodeGenOptions::FramePointerKind::All:
FuncAttrs.addAttribute("frame-pointer",
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3 changes: 3 additions & 0 deletions clang/lib/CodeGen/CodeGenModule.cpp
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Expand Up @@ -1506,6 +1506,9 @@ void CodeGenModule::Release() {
case CodeGenOptions::FramePointerKind::Reserved:
getModule().setFramePointer(llvm::FramePointerKind::Reserved);
break;
case CodeGenOptions::FramePointerKind::NonLeafNoReserve:
getModule().setFramePointer(llvm::FramePointerKind::NonLeafNoReserve);
break;
case CodeGenOptions::FramePointerKind::NonLeaf:
getModule().setFramePointer(llvm::FramePointerKind::NonLeaf);
break;
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3 changes: 3 additions & 0 deletions clang/lib/Driver/ToolChains/Clang.cpp
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Expand Up @@ -5748,6 +5748,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
case CodeGenOptions::FramePointerKind::Reserved:
FPKeepKindStr = "-mframe-pointer=reserved";
break;
case CodeGenOptions::FramePointerKind::NonLeafNoReserve:
FPKeepKindStr = "-mframe-pointer=non-leaf-no-reserve";
break;
case CodeGenOptions::FramePointerKind::NonLeaf:
FPKeepKindStr = "-mframe-pointer=non-leaf";
break;
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44 changes: 30 additions & 14 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Expand Up @@ -222,26 +222,38 @@ static bool framePointerImpliesLeafFramePointer(const llvm::opt::ArgList &Args,
clang::CodeGenOptions::FramePointerKind
getFramePointerKind(const llvm::opt::ArgList &Args,
const llvm::Triple &Triple) {
// There are three things to consider here:
// There are four things to consider here:
// * Should a frame record be created for non-leaf functions?
// * Should a frame record be created for leaf functions?
// * Is the frame pointer register reserved, i.e. must it always point to
// either a new, valid frame record or be un-modified?
// * Is the frame pointer register reserved in non-leaf functions?
// i.e. must it always point to either a new, valid frame record or be
// un-modified?
// * Is the frame pointer register reserved in leaf functions?
//
// Not all combinations of these are valid:
// * It's not useful to have leaf frame records without non-leaf ones.
// * It's not useful to have frame records without reserving the frame
// pointer.
//
// | Non-leaf | Leaf | Reserved |
// | N | N | N | FramePointerKind::None
// | N | N | Y | FramePointerKind::Reserved
// | N | Y | N | Invalid
// | N | Y | Y | Invalid
// | Y | N | N | Invalid
// | Y | N | Y | FramePointerKind::NonLeaf
// | Y | Y | N | Invalid
// | Y | Y | Y | FramePointerKind::All
// | Non-leaf | Leaf | Reserved In Non-Leaf | Reserved In Leaf |
// |----------|------|-----------------------|------------------|
// | N | N | N | N |
// FramePointerKind::None | N | N | N | Y |
// Invalid | N | N | Y | N |
// Invalid | N | N | Y | Y |
// FramePointerKind::Reserved | N | Y | N | N |
// Invalid | N | Y | N | Y |
// Invalid | N | Y | Y | N |
// Invalid | N | Y | Y | Y |
// Invalid | Y | N | N | N |
// Invalid | Y | N | N | Y |
// Invalid | Y | N | Y | N |
// FramePointerKind::NonLeafNoReserve | Y | N | Y | Y |
// FramePointerKind::NonLeaf | Y | Y | N | N |
// Invalid | Y | Y | N | Y |
// Invalid | Y | Y | Y | N |
// Invalid | Y | Y | Y | Y |
// FramePointerKind::All
//
// The FramePointerKind::Reserved case is currently only reachable for Arm,
// which has the -mframe-chain= option which can (in combination with
Expand All @@ -261,12 +273,16 @@ getFramePointerKind(const llvm::opt::ArgList &Args,
clang::driver::options::OPT_mno_omit_leaf_frame_pointer,
clang::driver::options::OPT_momit_leaf_frame_pointer, DefaultLeafFP);

bool FPRegReserved = EnableFP || mustMaintainValidFrameChain(Args, Triple);
bool FPRegReserved = mustMaintainValidFrameChain(Args, Triple);

if (EnableFP) {
if (EnableLeafFP)
return clang::CodeGenOptions::FramePointerKind::All;
return clang::CodeGenOptions::FramePointerKind::NonLeaf;

if (FPRegReserved)
return clang::CodeGenOptions::FramePointerKind::NonLeaf;

return clang::CodeGenOptions::FramePointerKind::NonLeafNoReserve;
}
if (FPRegReserved)
return clang::CodeGenOptions::FramePointerKind::Reserved;
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3 changes: 3 additions & 0 deletions clang/lib/Driver/ToolChains/Flang.cpp
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Expand Up @@ -1064,6 +1064,9 @@ void Flang::ConstructJob(Compilation &C, const JobAction &JA,
case CodeGenOptions::FramePointerKind::Reserved:
FPKeepKindStr = "-mframe-pointer=reserved";
break;
case CodeGenOptions::FramePointerKind::NonLeafNoReserve:
FPKeepKindStr = "-mframe-pointer=non-leaf-no-reserve";
break;
case CodeGenOptions::FramePointerKind::NonLeaf:
FPKeepKindStr = "-mframe-pointer=non-leaf";
break;
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8 changes: 4 additions & 4 deletions clang/test/Driver/frame-pointer-elim.c
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@@ -1,7 +1,7 @@
// KEEP-ALL-NOT: warning: argument unused
// KEEP-ALL: "-mframe-pointer=all"
// KEEP-NON-LEAF-NOT: warning: argument unused
// KEEP-NON-LEAF: "-mframe-pointer=non-leaf"
// KEEP-NON-LEAF: "-mframe-pointer=non-leaf-no-reserve"
// KEEP-NONE-NOT: warning: argument unused
// KEEP-NONE: "-mframe-pointer=none"
// KEEP-RESERVED-NOT: warning: argument unused
Expand Down Expand Up @@ -73,17 +73,17 @@
// RUN: %clang -### -target armv7s-apple-ios -fomit-frame-pointer %s 2>&1 | \
// RUN: FileCheck --check-prefix=WARN-OMIT-7S %s
// WARN-OMIT-7S: warning: optimization flag '-fomit-frame-pointer' is not supported for target 'armv7s'
// WARN-OMIT-7S: "-mframe-pointer=non-leaf"
// WARN-OMIT-7S: "-mframe-pointer=non-leaf-no-reserve"

// RUN: %clang -### -target armv7k-apple-watchos -fomit-frame-pointer %s 2>&1 | \
// RUN: FileCheck --check-prefix=WARN-OMIT-7K %s
// WARN-OMIT-7K: warning: optimization flag '-fomit-frame-pointer' is not supported for target 'armv7k'
// WARN-OMIT-7K: "-mframe-pointer=non-leaf"
// WARN-OMIT-7K: "-mframe-pointer=non-leaf-no-reserve"

// RUN: %clang -### -target armv7s-apple-ios8.0 -momit-leaf-frame-pointer %s 2>&1 | \
// RUN: FileCheck --check-prefix=WARN-OMIT-LEAF-7S %s
// WARN-OMIT-LEAF-7S-NOT: warning: optimization flag '-momit-leaf-frame-pointer' is not supported for target 'armv7s'
// WARN-OMIT-LEAF-7S: "-mframe-pointer=non-leaf"
// WARN-OMIT-LEAF-7S: "-mframe-pointer=non-leaf-no-reserve"

// On AArch64, PS4, PS5, and VE, default to omitting the frame pointer on leaf
// functions
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2 changes: 1 addition & 1 deletion clang/test/Driver/fuchsia.c
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Expand Up @@ -68,7 +68,7 @@
// RUN: %clang -### %s --target=aarch64-unknown-fuchsia -O3 2>&1 \
// RUN: | FileCheck %s -check-prefix=CHECK-FP-NONE
// CHECK-FP-ALL: "-mframe-pointer=all"
// CHECK-FP-NONLEAF: "-mframe-pointer=non-leaf"
// CHECK-FP-NONLEAF: "-mframe-pointer=non-leaf-no-reserve"
// CHECK-FP-NONE: "-mframe-pointer=none"

// RUN: not %clang -### %s --target=x86_64-unknown-fuchsia -rtlib=libgcc 2>&1 \
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8 changes: 7 additions & 1 deletion llvm/include/llvm/Support/CodeGen.h
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Expand Up @@ -115,7 +115,13 @@ namespace llvm {
};

// Specify what functions should keep the frame pointer.
enum class FramePointerKind { None, NonLeaf, All, Reserved };
enum class FramePointerKind {
None,
NonLeaf,
All,
Reserved,
NonLeafNoReserve
};

// Specify what type of zeroing callee-used registers.
namespace ZeroCallUsedRegs {
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5 changes: 5 additions & 0 deletions llvm/lib/CodeGen/CommandFlags.cpp
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Expand Up @@ -211,6 +211,9 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
clEnumValN(FramePointerKind::All, "all",
"Disable frame pointer elimination"),
clEnumValN(FramePointerKind::NonLeaf, "non-leaf",
"Disable frame pointer elimination for non-leaf frame but "
"reserve the register in leaf functions"),
clEnumValN(FramePointerKind::NonLeafNoReserve, "non-leaf-no-reserve",
"Disable frame pointer elimination for non-leaf frame"),
clEnumValN(FramePointerKind::Reserved, "reserved",
"Enable frame pointer elimination, but reserve the frame "
Expand Down Expand Up @@ -695,6 +698,8 @@ void codegen::setFunctionAttributes(StringRef CPU, StringRef Features,
NewAttrs.addAttribute("frame-pointer", "all");
else if (getFramePointerUsage() == FramePointerKind::NonLeaf)
NewAttrs.addAttribute("frame-pointer", "non-leaf");
else if (getFramePointerUsage() == FramePointerKind::NonLeafNoReserve)
NewAttrs.addAttribute("frame-pointer", "non-leaf-no-reserve");
else if (getFramePointerUsage() == FramePointerKind::Reserved)
NewAttrs.addAttribute("frame-pointer", "reserved");
else if (getFramePointerUsage() == FramePointerKind::None)
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3 changes: 2 additions & 1 deletion llvm/lib/CodeGen/TargetOptionsImpl.cpp
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Expand Up @@ -30,7 +30,7 @@ bool TargetOptions::DisableFramePointerElim(const MachineFunction &MF) const {
StringRef FP = FPAttr.getValueAsString();
if (FP == "all")
return true;
if (FP == "non-leaf")
if (FP == "non-leaf" || FP == "non-leaf-no-reserve")
return MF.getFrameInfo().hasCalls();
if (FP == "none" || FP == "reserved")
return false;
Expand All @@ -45,6 +45,7 @@ bool TargetOptions::FramePointerIsReserved(const MachineFunction &MF) const {

return StringSwitch<bool>(FPAttr.getValueAsString())
.Cases("all", "non-leaf", "reserved", true)
.Case(("non-leaf-no-reserve"), MF.getFrameInfo().hasCalls())
.Case("none", false);
}

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3 changes: 3 additions & 0 deletions llvm/lib/IR/Function.cpp
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Expand Up @@ -396,6 +396,9 @@ Function *Function::createWithDefaultAttr(FunctionType *Ty,
case FramePointerKind::NonLeaf:
B.addAttribute("frame-pointer", "non-leaf");
break;
case FramePointerKind::NonLeafNoReserve:
B.addAttribute("frame-pointer", "non-leaf-no-reserve");
break;
case FramePointerKind::All:
B.addAttribute("frame-pointer", "all");
break;
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3 changes: 2 additions & 1 deletion llvm/lib/IR/Verifier.cpp
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Expand Up @@ -2484,7 +2484,8 @@ void Verifier::verifyFunctionAttrs(FunctionType *FT, AttributeList Attrs,

if (Attribute FPAttr = Attrs.getFnAttr("frame-pointer"); FPAttr.isValid()) {
StringRef FP = FPAttr.getValueAsString();
if (FP != "all" && FP != "non-leaf" && FP != "none" && FP != "reserved")
if (FP != "all" && FP != "non-leaf" && FP != "none" && FP != "reserved" &&
FP != "non-leaf-no-reserve")
CheckFailed("invalid value for 'frame-pointer' attribute: " + FP, V);
}

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