[ARM] Fix -mno-omit-leaf-frame-pointer flag doesn't works on 32-bit A…

…RM (llvm#109628) The -mno-omit-leaf-frame-pointer flag works on 32-bit ARM architectures and addresses the bug reported in llvm#108019
efcs · Oct 22, 2024 · 2e7dea5 · 2e7dea5
1 parent 2dc4911
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diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -612,6 +612,11 @@ X86 Support
 Arm and AArch64 Support
 ^^^^^^^^^^^^^^^^^^^^^^^
 
+- In the ARM Target, the frame pointer (FP) of a leaf function can be retained
+  by using the ``-fno-omit-frame-pointer`` option. If you want to eliminate the FP
+  in leaf functions after enabling ``-fno-omit-frame-pointer``, you can do so by adding
+  the ``-momit-leaf-frame-pointer`` option.
+
 Android Support
 ^^^^^^^^^^^^^^^
 

diff --git a/llvm/docs/ReleaseNotes.md b/llvm/docs/ReleaseNotes.md
@@ -125,6 +125,12 @@ Changes to the ARM Backend
   the required alignment space with a sequence of `0x0` bytes (the requested
   fill value) rather than NOPs.
 
+* The default behavior for frame pointers in leaf functions has been updated.
+  When the `-fno-omit-frame-pointer` option is specified, `FPKeepKindStr` is
+  set to `-mframe-pointer=all`, meaning the frame pointer (FP) is now retained
+  in leaf functions by default. To eliminate the frame pointer in leaf functions,
+  you must explicitly use the `-momit-leaf-frame-pointer` option.
+
 Changes to the AVR Backend
 --------------------------
 

diff --git a/llvm/include/llvm/CodeGen/TargetFrameLowering.h b/llvm/include/llvm/CodeGen/TargetFrameLowering.h
@@ -277,12 +277,6 @@ class TargetFrameLowering {
     return false;
   }
 
-  /// Return true if the target wants to keep the frame pointer regardless of
-  /// the function attribute "frame-pointer".
-  virtual bool keepFramePointer(const MachineFunction &MF) const {
-    return false;
-  }
-
   /// hasFP - Return true if the specified function should have a dedicated
   /// frame pointer register. For most targets this is true only if the function
   /// has variable sized allocas or if frame pointer elimination is disabled.

diff --git a/llvm/lib/CodeGen/TargetOptionsImpl.cpp b/llvm/lib/CodeGen/TargetOptionsImpl.cpp
@@ -22,10 +22,6 @@ using namespace llvm;
 /// DisableFramePointerElim - This returns true if frame pointer elimination
 /// optimization should be disabled for the given machine function.
 bool TargetOptions::DisableFramePointerElim(const MachineFunction &MF) const {
-  // Check to see if the target want to forcibly keep frame pointer.
-  if (MF.getSubtarget().getFrameLowering()->keepFramePointer(MF))
-    return true;
-
   const Function &F = MF.getFunction();
 
   if (!F.hasFnAttribute("frame-pointer"))
@@ -41,10 +37,6 @@ bool TargetOptions::DisableFramePointerElim(const MachineFunction &MF) const {
 }
 
 bool TargetOptions::FramePointerIsReserved(const MachineFunction &MF) const {
-  // Check to see if the target want to forcibly keep frame pointer.
-  if (MF.getSubtarget().getFrameLowering()->keepFramePointer(MF))
-    return true;
-
   const Function &F = MF.getFunction();
 
   if (!F.hasFnAttribute("frame-pointer"))

diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.cpp b/llvm/lib/Target/ARM/ARMFrameLowering.cpp
@@ -330,6 +330,10 @@ bool ARMFrameLowering::hasFP(const MachineFunction &MF) const {
   const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
   const MachineFrameInfo &MFI = MF.getFrameInfo();
 
+  // Check to see if the target want to forcibly keep frame pointer.
+  if (keepFramePointer(MF))
+    return true;
+
   // ABI-required frame pointer.
   if (MF.getTarget().Options.DisableFramePointerElim(MF))
     return true;
@@ -2403,7 +2407,8 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
   // to take advantage the eliminateFrameIndex machinery. This also ensures it
   // is spilled in the order specified by getCalleeSavedRegs() to make it easier
   // to combine multiple loads / stores.
-  bool CanEliminateFrame = !(requiresAAPCSFrameRecord(MF) && hasFP(MF));
+  bool CanEliminateFrame = !(requiresAAPCSFrameRecord(MF) && hasFP(MF)) &&
+                           !MF.getTarget().Options.DisableFramePointerElim(MF);
   bool CS1Spilled = false;
   bool LRSpilled = false;
   unsigned NumGPRSpills = 0;

diff --git a/llvm/lib/Target/ARM/ARMFrameLowering.h b/llvm/lib/Target/ARM/ARMFrameLowering.h
@@ -41,7 +41,7 @@ class ARMFrameLowering : public TargetFrameLowering {
                               MutableArrayRef<CalleeSavedInfo> CSI,
                               const TargetRegisterInfo *TRI) const override;
 
-  bool keepFramePointer(const MachineFunction &MF) const override;
+  bool keepFramePointer(const MachineFunction &MF) const;
 
   bool enableCalleeSaveSkip(const MachineFunction &MF) const override;
 

diff --git a/llvm/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll b/llvm/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll
@@ -9,7 +9,7 @@
 
 @oStruct = external global %struct.Outer, align 4
 
-define void @main(i8 %val8) nounwind {
+define void @main(i8 %val8) nounwind "frame-pointer"="none" {
 ; CHECK-LABEL: main:
 ; CHECK:       @ %bb.0: @ %for.body.lr.ph
 ; CHECK-NEXT:    movw r0, :lower16:(L_oStruct$non_lazy_ptr-(LPC0_0+4))

diff --git a/llvm/test/CodeGen/ARM/2011-12-19-sjlj-clobber.ll b/llvm/test/CodeGen/ARM/2011-12-19-sjlj-clobber.ll
@@ -3,7 +3,7 @@
 ; Radar 10567930: Make sure that all the caller-saved registers are saved and
 ; restored in a function with setjmp/longjmp EH.  In particular, r6 was not
 ; being saved here.
-; CHECK: push {r4, r5, r6, r7, lr}
+; CHECK: push.w {r4, r5, r6, r7, r8, r10, r11, lr}
 
 %0 = type opaque
 %struct.NSConstantString = type { ptr, i32, ptr, i32 }

diff --git a/llvm/test/CodeGen/ARM/arm-shrink-wrapping.ll b/llvm/test/CodeGen/ARM/arm-shrink-wrapping.ll
@@ -1732,7 +1732,7 @@ if.end:
 ; Another infinite loop test this time with two nested infinite loop.
 ; infiniteloop3
 ; bx lr
-define void @infiniteloop3() "frame-pointer"="all" {
+define void @infiniteloop3() "frame-pointer"="none" {
 ; ARM-LABEL: infiniteloop3:
 ; ARM:       @ %bb.0: @ %entry
 ; ARM-NEXT:    mov r0, #0

diff --git a/llvm/test/CodeGen/ARM/atomic-load-store.ll b/llvm/test/CodeGen/ARM/atomic-load-store.ll
@@ -324,18 +324,17 @@ define void @test_old_store_64bit(ptr %p, i64 %v) {
 ;
 ; ARMOPTNONE-LABEL: test_old_store_64bit:
 ; ARMOPTNONE:       @ %bb.0:
-; ARMOPTNONE-NEXT:    push {r4, r5, r7, lr}
-; ARMOPTNONE-NEXT:    add r7, sp, #8
-; ARMOPTNONE-NEXT:    push {r8, r10, r11}
-; ARMOPTNONE-NEXT:    sub sp, sp, #24
-; ARMOPTNONE-NEXT:    str r0, [sp, #4] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    str r2, [sp, #8] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    str r1, [sp, #12] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    dmb ish
-; ARMOPTNONE-NEXT:    ldr r1, [r0]
-; ARMOPTNONE-NEXT:    ldr r0, [r0, #4]
-; ARMOPTNONE-NEXT:    str r1, [sp, #16] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    str r0, [sp, #20] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    push	{r4, r5, r7, r8, r10, r11, lr}
+; ARMOPTNONE-NEXT:    add	r7, sp, #20
+; ARMOPTNONE-NEXT:    sub	sp, sp, #24
+; ARMOPTNONE-NEXT:    str	r0, [sp, #4] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    str	r2, [sp, #8] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    str	r1, [sp, #12] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    dmb	ish
+; ARMOPTNONE-NEXT:    ldr	r1, [r0]
+; ARMOPTNONE-NEXT:    ldr	r0, [r0, #4]
+; ARMOPTNONE-NEXT:    str	r1, [sp, #16] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    str	r0, [sp, #20] @ 4-byte Spill
 ; ARMOPTNONE-NEXT:    b LBB5_1
 ; ARMOPTNONE-NEXT:  LBB5_1: @ %atomicrmw.start
 ; ARMOPTNONE-NEXT:    @ =>This Loop Header: Depth=1
@@ -382,8 +381,7 @@ define void @test_old_store_64bit(ptr %p, i64 %v) {
 ; ARMOPTNONE-NEXT:  LBB5_5: @ %atomicrmw.end
 ; ARMOPTNONE-NEXT:    dmb ish
 ; ARMOPTNONE-NEXT:    sub sp, r7, #20
-; ARMOPTNONE-NEXT:    pop {r8, r10, r11}
-; ARMOPTNONE-NEXT:    pop {r4, r5, r7, pc}
+; ARMOPTNONE-NEXT:    pop	{r4, r5, r7, r8, r10, r11, pc}
 ;
 ; THUMBTWO-LABEL: test_old_store_64bit:
 ; THUMBTWO:       @ %bb.0:
@@ -864,20 +862,19 @@ define void @store_atomic_f64__seq_cst(ptr %ptr, double %val1) {
 ;
 ; ARMOPTNONE-LABEL: store_atomic_f64__seq_cst:
 ; ARMOPTNONE:       @ %bb.0:
-; ARMOPTNONE-NEXT:    push {r4, r5, r7, lr}
-; ARMOPTNONE-NEXT:    add r7, sp, #8
-; ARMOPTNONE-NEXT:    push {r8, r10, r11}
-; ARMOPTNONE-NEXT:    sub sp, sp, #24
-; ARMOPTNONE-NEXT:    str r0, [sp, #4] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    vmov d16, r1, r2
-; ARMOPTNONE-NEXT:    vmov r1, r2, d16
-; ARMOPTNONE-NEXT:    str r2, [sp, #8] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    str r1, [sp, #12] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    dmb ish
-; ARMOPTNONE-NEXT:    ldr r1, [r0]
-; ARMOPTNONE-NEXT:    ldr r0, [r0, #4]
-; ARMOPTNONE-NEXT:    str r1, [sp, #16] @ 4-byte Spill
-; ARMOPTNONE-NEXT:    str r0, [sp, #20] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    push	{r4, r5, r7, r8, r10, r11, lr}
+; ARMOPTNONE-NEXT:    add	r7, sp, #20
+; ARMOPTNONE-NEXT:    sub	sp, sp, #24
+; ARMOPTNONE-NEXT:    str	r0, [sp, #4] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    vmov	d16, r1, r2
+; ARMOPTNONE-NEXT:    vmov	r1, r2, d16
+; ARMOPTNONE-NEXT:    str	r2, [sp, #8] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    str	r1, [sp, #12] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    dmb	ish
+; ARMOPTNONE-NEXT:    ldr	r1, [r0]
+; ARMOPTNONE-NEXT:    ldr	r0, [r0, #4]
+; ARMOPTNONE-NEXT:    str	r1, [sp, #16] @ 4-byte Spill
+; ARMOPTNONE-NEXT:    str	r0, [sp, #20] @ 4-byte Spill
 ; ARMOPTNONE-NEXT:    b LBB13_1
 ; ARMOPTNONE-NEXT:  LBB13_1: @ %atomicrmw.start
 ; ARMOPTNONE-NEXT:    @ =>This Loop Header: Depth=1
@@ -924,8 +921,7 @@ define void @store_atomic_f64__seq_cst(ptr %ptr, double %val1) {
 ; ARMOPTNONE-NEXT:  LBB13_5: @ %atomicrmw.end
 ; ARMOPTNONE-NEXT:    dmb ish
 ; ARMOPTNONE-NEXT:    sub sp, r7, #20
-; ARMOPTNONE-NEXT:    pop {r8, r10, r11}
-; ARMOPTNONE-NEXT:    pop {r4, r5, r7, pc}
+; ARMOPTNONE-NEXT:    pop	{r4, r5, r7, r8, r10, r11, pc}
 ;
 ; THUMBTWO-LABEL: store_atomic_f64__seq_cst:
 ; THUMBTWO:       @ %bb.0:

diff --git a/llvm/test/CodeGen/ARM/call-tc.ll b/llvm/test/CodeGen/ARM/call-tc.ll
@@ -17,7 +17,7 @@ define void @t1() "frame-pointer"="all" {
         ret void
 }
 
-define void @t2() "frame-pointer"="all" {
+define void @t2() "frame-pointer"="none" {
 ; CHECKV6-LABEL: t2:
 ; CHECKV6: bx r0
 ; CHECKT2D-LABEL: t2:
@@ -102,7 +102,7 @@ bb:
 
 ; Make sure codegenprep is duplicating ret instructions to enable tail calls.
 ; rdar://11140249
-define i32 @t8(i32 %x) nounwind ssp "frame-pointer"="all" {
+define i32 @t8(i32 %x) nounwind ssp "frame-pointer"="none" {
 entry:
 ; CHECKT2D-LABEL: t8:
 ; CHECKT2D-NOT: push

diff --git a/llvm/test/CodeGen/ARM/debug-frame.ll b/llvm/test/CodeGen/ARM/debug-frame.ll
@@ -526,7 +526,7 @@ entry:
 ; Test 4
 ;-------------------------------------------------------------------------------
 
-define void @test4() nounwind {
+define void @test4() nounwind "frame-pointer"="none" {
 entry:
   ret void
 }

diff --git a/llvm/test/CodeGen/ARM/ehabi.ll b/llvm/test/CodeGen/ARM/ehabi.ll
@@ -575,7 +575,7 @@ entry:
 ; Test 4
 ;-------------------------------------------------------------------------------
 
-define void @test4() nounwind {
+define void @test4() nounwind "frame-pointer"="none" {
 entry:
   ret void
 }

diff --git a/llvm/test/CodeGen/ARM/fast-isel-frameaddr.ll b/llvm/test/CodeGen/ARM/fast-isel-frameaddr.ll
@@ -16,7 +16,7 @@ entry:
 ; DARWIN-THUMB2: mov r0, r7
 
 ; LINUX-ARM-LABEL: frameaddr_index0:
-; LINUX-ARM: push {r11, lr}
+; LINUX-ARM: push {r11}
 ; LINUX-ARM: mov r11, sp
 ; LINUX-ARM: mov r0, r11
 
@@ -42,7 +42,7 @@ entry:
 ; DARWIN-THUMB2: ldr r0, [r7]
 
 ; LINUX-ARM-LABEL: frameaddr_index1:
-; LINUX-ARM: push {r11, lr}
+; LINUX-ARM: push {r11}
 ; LINUX-ARM: mov r11, sp
 ; LINUX-ARM: ldr r0, [r11]
 
@@ -73,7 +73,7 @@ entry:
 ; DARWIN-THUMB2: ldr r0, [r0]
 
 ; LINUX-ARM-LABEL: frameaddr_index3:
-; LINUX-ARM: push {r11, lr}
+; LINUX-ARM: push {r11}
 ; LINUX-ARM: mov r11, sp
 ; LINUX-ARM: ldr r0, [r11]
 ; LINUX-ARM: ldr r0, [r0]

diff --git a/llvm/test/CodeGen/ARM/frame-chain.ll b/llvm/test/CodeGen/ARM/frame-chain.ll
@@ -10,11 +10,14 @@
 define dso_local noundef i32 @leaf(i32 noundef %0) {
 ; LEAF-FP-LABEL: leaf:
 ; LEAF-FP:       @ %bb.0:
-; LEAF-FP-NEXT:    .pad #4
-; LEAF-FP-NEXT:    sub sp, sp, #4
-; LEAF-FP-NEXT:    str r0, [sp]
+; LEAF-FP-NEXT:    .save {r11, lr}
+; LEAF-FP-NEXT:    push {r11, lr}
+; LEAF-FP-NEXT:    .setfp r11, sp
+; LEAF-FP-NEXT:    mov r11, sp
+; LEAF-FP-NEXT:    push {r0}
 ; LEAF-FP-NEXT:    add r0, r0, #4
-; LEAF-FP-NEXT:    add sp, sp, #4
+; LEAF-FP-NEXT:    mov sp, r11
+; LEAF-FP-NEXT:    pop {r11, lr}
 ; LEAF-FP-NEXT:    mov pc, lr
 ;
 ; LEAF-FP-AAPCS-LABEL: leaf:

diff --git a/llvm/test/CodeGen/ARM/ifcvt5.ll b/llvm/test/CodeGen/ARM/ifcvt5.ll
@@ -5,7 +5,7 @@
 
 @x = external global ptr		; <ptr> [#uses=1]
 
-define void @foo(i32 %a) "frame-pointer"="all" {
+define void @foo(i32 %a) "frame-pointer"="none" {
 ; A8-LABEL: foo:
 ; A8:       @ %bb.0: @ %entry
 ; A8-NEXT:    movw r1, :lower16:(L_x$non_lazy_ptr-(LPC0_0+8))

diff --git a/llvm/test/CodeGen/ARM/ldrd.ll b/llvm/test/CodeGen/ARM/ldrd.ll
@@ -168,7 +168,7 @@ define void @ldrd_postupdate_inc(ptr %p0) "frame-pointer"="all" {
 ; NORMAL: strd r1, r2, [r0], #-8
 ; CONSERVATIVE-NOT: strd
 ; CHECK: bx lr
-define ptr @strd_postupdate_dec(ptr %p0, i32 %v0, i32 %v1) "frame-pointer"="all" {
+define ptr @strd_postupdate_dec(ptr %p0, i32 %v0, i32 %v1) "frame-pointer"="none" {
   %p0.1 = getelementptr i32, ptr %p0, i32 1
   store i32 %v0, ptr %p0
   store i32 %v1, ptr %p0.1
@@ -180,7 +180,7 @@ define ptr @strd_postupdate_dec(ptr %p0, i32 %v0, i32 %v1) "frame-pointer"="all"
 ; NORMAL: strd r1, r2, [r0], #8
 ; CONSERVATIVE-NOT: strd
 ; CHECK: bx lr
-define ptr @strd_postupdate_inc(ptr %p0, i32 %v0, i32 %v1) "frame-pointer"="all" {
+define ptr @strd_postupdate_inc(ptr %p0, i32 %v0, i32 %v1) "frame-pointer"="none" {
   %p0.1 = getelementptr i32, ptr %p0, i32 1
   store i32 %v0, ptr %p0
   store i32 %v1, ptr %p0.1

diff --git a/llvm/test/CodeGen/ARM/stack-frame-layout-remarks.ll b/llvm/test/CodeGen/ARM/stack-frame-layout-remarks.ll
@@ -51,7 +51,7 @@ declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
 ; BOTH:  [SP-8]{{.+}}8{{.+}}4
 ; DEBUG: a @ dot.c:13
 ; STRIPPED-NOT: a @ dot.c:13
-define void @cleanup_array(ptr %0) #1 {
+define void @cleanup_array(ptr %0) #3 {
   %2 = alloca ptr, align 8
   store ptr %0, ptr %2, align 8
   call void @llvm.dbg.declare(metadata ptr %2, metadata !41, metadata !DIExpression()), !dbg !46
@@ -62,7 +62,7 @@ define void @cleanup_array(ptr %0) #1 {
 ; BOTH:  [SP-8]{{.+}}8{{.+}}4
 ; DEBUG: res @ dot.c:21
 ; STRIPPED-NOT: res @ dot.c:21
-define void @cleanup_result(ptr %0) #1 {
+define void @cleanup_result(ptr %0) #3 {
   %2 = alloca ptr, align 8
   store ptr %0, ptr %2, align 8
   call void @llvm.dbg.declare(metadata ptr %2, metadata !47, metadata !DIExpression()), !dbg !51
@@ -92,7 +92,7 @@ define void @cleanup_result(ptr %0) #1 {
 ; BOTH:  [SP-40]{{.+}}4{{.+}}4
 ; DEBUG: i @ dot.c:55
 ; STRIPPED-NOT: i @ dot.c:55
-define i32 @do_work(ptr %0, ptr %1, ptr %2) #1 {
+define i32 @do_work(ptr %0, ptr %1, ptr %2) #3 {
   %4 = alloca i32, align 4
   %5 = alloca ptr, align 8
   %6 = alloca ptr, align 8
@@ -144,7 +144,7 @@ define i32 @do_work(ptr %0, ptr %1, ptr %2) #1 {
 ; BOTH:  [SP-20]{{.+}}4{{.*}}4
 ; DEBUG: i @ dot.c:69
 ; STRIPPED-NOT: i @ dot.c:69
-define ptr @gen_array(i32 %0) #1 {
+define ptr @gen_array(i32 %0) #3 {
   %2 = alloca ptr, align 8
   %3 = alloca i32, align 4
   %4 = alloca ptr, align 8
@@ -227,6 +227,7 @@ uselistorder ptr @llvm.dbg.declare, { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
 attributes #0 = { nocallback nofree nosync nounwind readnone speculatable willreturn }
 attributes #1 = { "frame-pointer"="all" }
 attributes #2 = { ssp "stack-protector-buffer-size"="5" "frame-pointer"="all" }
+attributes #3 = { "frame-pointer"="none" }
 
 !llvm.dbg.cu = !{!0, !2}
 !llvm.module.flags = !{!18, !19, !20, !21, !22, !23, !24}

diff --git a/llvm/test/CodeGen/ARM/stack-size-section.ll b/llvm/test/CodeGen/ARM/stack-size-section.ll
@@ -29,4 +29,4 @@ define void @dynalloc(i32 %N) #0 {
   ret void
 }
 
-attributes #0 = { "frame-pointer"="all" }
+attributes #0 = { "frame-pointer"="none" }