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Enable frame pointer for non-leaf functions on Android #97614

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Merged
merged 1 commit into from
Jul 8, 2024
+14 −18
Merged

Enable frame pointer for non-leaf functions on Android #97614

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17 changes: 3 additions & 14 deletions clang/lib/Driver/ToolChains/CommonArgs.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -78,19 +78,8 @@ static bool useFramePointerForTargetByDefault(const llvm::opt::ArgList &Args,
!Args.hasArg(clang::driver::options::OPT_mfentry))
return true;

if (Triple.isAndroid()) {
switch (Triple.getArch()) {
case llvm::Triple::aarch64:
case llvm::Triple::arm:
case llvm::Triple::armeb:
case llvm::Triple::thumb:
case llvm::Triple::thumbeb:
case llvm::Triple::riscv64:
return true;
default:
break;
}
}
if (Triple.isAndroid())
return true;

switch (Triple.getArch()) {
case llvm::Triple::xcore:
Expand Down Expand Up @@ -166,7 +155,7 @@ static bool useFramePointerForTargetByDefault(const llvm::opt::ArgList &Args,

static bool useLeafFramePointerForTargetByDefault(const llvm::Triple &Triple) {
if (Triple.isAArch64() || Triple.isPS() || Triple.isVE() ||
(Triple.isAndroid() && Triple.isRISCV64()))
(Triple.isAndroid() && !Triple.isARM()))
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Did you mean to miss out Thumb? isARM is only true for arm-*, armeb-* triples, you would need an isThumb call to also cover thumb-* and thumbeb-* triples.

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I didn't intentionally remove frame pointer for leaf functions for thumb in Android. But I also don't have reason to add it back:

  1. On Android, we can't rely on stack frame pointer based unwinding for arm32 binaries. Because arm and thumb use different registers as frame pointers.
  2. On other architectures that we want to support stack frame pointer based unwinding (aarch64, riscv64, x86_64), we don't need frame pointer for leaf functions.

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In https://godbolt.org/z/Krc3eq46h, I tried generating thumb instruction with and without -mno-omit-leaf-frame-pointer. They generate the same instructions not setting up frame pointers for leaf functions.

return false;

return true;
Expand Down
15 changes: 11 additions & 4 deletions clang/test/Driver/frame-pointer.c
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Expand Up @@ -4,6 +4,9 @@
// RUN: %clang --target=i386-pc-linux -### -S -O3 %s 2>&1 | FileCheck -check-prefix=CHECK3-32 %s
// RUN: %clang --target=i386-pc-linux -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECKs-32 %s

// RUN: %clang --target=i386-linux-android -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s
// RUN: %clang --target=i386-linux-android -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s
// RUN: %clang --target=i386-linux-android -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s

// RUN: %clang --target=x86_64-pc-linux -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK0-64 %s
// RUN: %clang --target=x86_64-pc-linux -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK1-64 %s
Expand All @@ -12,6 +15,10 @@
// RUN: %clang --target=x86_64-pc-linux -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECKs-64 %s
// RUN: %clang --target=x86_64-pc-win32-macho -### -S -O3 %s 2>&1 | FileCheck -check-prefix=CHECK-MACHO-64 %s

// RUN: %clang --target=x86_64-linux-android -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s
// RUN: %clang --target=x86_64-linux-android -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s
// RUN: %clang --target=x86_64-linux-android -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s

// Trust the above to get the optimizations right, and just test other targets
// that want this by default.
// RUN: %clang --target=s390x-pc-linux -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK0-64 %s
Expand Down Expand Up @@ -57,9 +64,9 @@
// RUN: %clang --target=riscv64-unknown-linux-gnu -### -S -O3 %s 2>&1 | FileCheck -check-prefix=CHECK3-64 %s
// RUN: %clang --target=riscv64-unknown-linux-gnu -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECKs-64 %s

// RUN: %clang --target=riscv64-linux-android -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID-64 %s
// RUN: %clang --target=riscv64-linux-android -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID-64 %s
// RUN: %clang --target=riscv64-linux-android -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID-64 %s
// RUN: %clang --target=riscv64-linux-android -### -S -O0 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s
// RUN: %clang --target=riscv64-linux-android -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s
// RUN: %clang --target=riscv64-linux-android -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-ANDROID %s

// RUN: %clang --target=loongarch32 -### -S -O0 %s -o %t.s 2>&1 | FileCheck -check-prefix=CHECK0-32 %s
// RUN: %clang --target=loongarch32 -### -S -O1 %s -o %t.s 2>&1 | FileCheck -check-prefix=CHECK1-32 %s
Expand All @@ -86,4 +93,4 @@
// CHECKs-64-NOT: -mframe-pointer=all
// CHECK-MACHO-64: -mframe-pointer=all

// CHECK-ANDROID-64: -mframe-pointer=non-leaf
// CHECK-ANDROID: -mframe-pointer=non-leaf
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