Driver: follow WoA ABI recommendations

The Windows on ARM ABI recommends that FPO be disabled.  This is since the
Windows on ARM ABI uses the FP for fast stack walking.  By paying the slight
cost of the loss of registers, a much faster backtrace is possible by using the
frame pointer since the pdata need not be consulted.  Furthermore, even if pdata
is not available, you can still more easily reconstruct the stack.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@249227 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index f20e5cd8ef8bec8a9c7674de3e7148285c779d25..7cccf09665ca7ea38d00cbf2e1272dbfdc3016fe 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -2655,6 +2655,10 @@ static bool shouldUseFramePointerForTarget(const ArgList &Args,
     switch (Triple.getArch()) {
     case llvm::Triple::x86:
       return !areOptimizationsEnabled(Args);
+    case llvm::Triple::arm:
+    case llvm::Triple::thumb:
+      // Windows on ARM builds with FPO disabled to aid fast stack walking
+      return true;
     default:
       // All other supported Windows ISAs use xdata unwind information, so frame
       // pointers are not generally useful.

diff --git a/test/Driver/woa-fp.c b/test/Driver/woa-fp.c
new file mode 100644 (file)
index 0000000..f851e93
--- /dev/null
+++ b/test/Driver/woa-fp.c
@@ -0,0 +1,40 @@
+// RUN: %clang -target armv7-windows-msvc -### -S %s -O0 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-msvc -### -S %s -O1 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-msvc -### -S %s -O2 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-msvc -### -S %s -O3 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-msvc -### -S %s -Os -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+
+// RUN: %clang -target armv7-windows-itanium -### -S %s -O0 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-itanium -### -S %s -O1 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-itanium -### -S %s -O2 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-itanium -### -S %s -O3 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+// RUN: %clang -target armv7-windows-itanium -### -S %s -Os -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-DEFAULT
+
+// RUN: %clang -target armv7-windows-msvc -fomit-frame-pointer -### -S %s -O0 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-msvc -fomit-frame-pointer -### -S %s -O1 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-msvc -fomit-frame-pointer -### -S %s -O2 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-msvc -fomit-frame-pointer -### -S %s -O3 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-msvc -fomit-frame-pointer -### -S %s -Os -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+
+// RUN: %clang -target armv7-windows-itanium -fomit-frame-pointer -### -S %s -O0 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-itanium -fomit-frame-pointer -### -S %s -O1 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-itanium -fomit-frame-pointer -### -S %s -O2 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-itanium -fomit-frame-pointer -### -S %s -O3 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+// RUN: %clang -target armv7-windows-itanium -fomit-frame-pointer -### -S %s -Os -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-FPO
+
+// RUN: %clang -target armv7-windows-msvc -fno-omit-frame-pointer -### -S %s -O0 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-msvc -fno-omit-frame-pointer -### -S %s -O1 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-msvc -fno-omit-frame-pointer -### -S %s -O2 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-msvc -fno-omit-frame-pointer -### -S %s -O3 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-msvc -fno-omit-frame-pointer -### -S %s -Os -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+
+// RUN: %clang -target armv7-windows-itanium -fno-omit-frame-pointer -### -S %s -O0 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-itanium -fno-omit-frame-pointer -### -S %s -O1 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-itanium -fno-omit-frame-pointer -### -S %s -O2 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-itanium -fno-omit-frame-pointer -### -S %s -O3 -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+// RUN: %clang -target armv7-windows-itanium -fno-omit-frame-pointer -### -S %s -Os -o /dev/null 2>&1 | FileCheck %s -check-prefix CHECK-NO-FPO
+
+// CHECK-DEFAULT: "-mdisable-fp-elim"
+// CHECK-FPO-NOT: "-mdisable-fp-elim"
+// CHECK-NO-FPO: "-mdisable-fp-elim"
+