ARM-Darwin: ignore and diagnose attempts to omit frame pointer.

iOS (and other 32-bit ARM variants) always require a valid frame pointer to
improve backtraces. Previously the -fomit-frame-pointer and
-momit-leaf-frame-pointer options were being silently discarded via hacks in
the backend. It's better if Clang configures itself to emit the correct IR and
warns about (ignored) attempts to override this.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@279546 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index 27bcd77ec4d85e32e43cf9f722a5c1d81924238d..33d2af09febd25e27038106e913b79229236ab18 100644 (file)
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -169,6 +169,9 @@ def warn_drv_optimization_value : Warning<"optimization level '%0' is not suppor
   InGroup<InvalidCommandLineArgument>;
 def warn_ignored_gcc_optimization : Warning<"optimization flag '%0' is not supported">,
   InGroup<IgnoredOptimizationArgument>;
+def warn_drv_unsupported_opt_for_target : Warning<
+  "optimization flag '%0' is not supported for target '%1'">,
+  InGroup<IgnoredOptimizationArgument>;
 def warn_c_kext : Warning<
   "ignoring -fapple-kext which is valid for C++ and Objective-C++ only">;
 def warn_drv_input_file_unused : Warning<

diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 68d5214fdfd2d5cb5858feb0be11b9382e718bef..4b8182e54b271019793bcb65690654634ac27d22 100644 (file)
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -1085,6 +1085,18 @@ DerivedArgList *Darwin::TranslateArgs(const DerivedArgList &Args,
     }
   }
 
+  auto Arch = tools::darwin::getArchTypeForMachOArchName(BoundArch);
+  if ((Arch == llvm::Triple::arm || Arch == llvm::Triple::thumb)) {
+    if (Args.hasFlag(options::OPT_fomit_frame_pointer,
+                     options::OPT_fno_omit_frame_pointer, false))
+      getDriver().Diag(clang::diag::warn_drv_unsupported_opt_for_target)
+          << "-fomit-frame-pointer" << BoundArch;
+    if (Args.hasFlag(options::OPT_momit_leaf_frame_pointer,
+                     options::OPT_mno_omit_leaf_frame_pointer, false))
+      getDriver().Diag(clang::diag::warn_drv_unsupported_opt_for_target)
+          << "-momit-leaf-frame-pointer" << BoundArch;
+  }
+
   return DAL;
 }
 

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 747f3ea57a12fe7dce375f02b3e1ab38d54d840c..895104e1c45109542fd5b41ae3a7bc0bcf1ffbfc 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -3232,8 +3232,20 @@ static bool areOptimizationsEnabled(const ArgList &Args) {
   return false;
 }
 
-static bool shouldUseFramePointerForTarget(const ArgList &Args,
-                                           const llvm::Triple &Triple) {
+static bool mustUseFramePointerForTarget(const llvm::Triple &Triple) {
+  switch (Triple.getArch()){
+  default:
+    return false;
+  case llvm::Triple::arm:
+  case llvm::Triple::thumb:
+    // ARM Darwin targets require a frame pointer to be always present to aid
+    // offline debugging via backtraces.
+    return Triple.isOSDarwin();
+  }
+}
+
+static bool useFramePointerForTargetByDefault(const ArgList &Args,
+                                              const llvm::Triple &Triple) {
   switch (Triple.getArch()) {
   case llvm::Triple::xcore:
   case llvm::Triple::wasm32:
@@ -3285,25 +3297,29 @@ static bool shouldUseFramePointer(const ArgList &Args,
                                   const llvm::Triple &Triple) {
   if (Arg *A = Args.getLastArg(options::OPT_fno_omit_frame_pointer,
                                options::OPT_fomit_frame_pointer))
-    return A->getOption().matches(options::OPT_fno_omit_frame_pointer);
+    return A->getOption().matches(options::OPT_fno_omit_frame_pointer) ||
+           mustUseFramePointerForTarget(Triple);
+
   if (Args.hasArg(options::OPT_pg))
     return true;
 
-  return shouldUseFramePointerForTarget(Args, Triple);
+  return useFramePointerForTargetByDefault(Args, Triple);
 }
 
 static bool shouldUseLeafFramePointer(const ArgList &Args,
                                       const llvm::Triple &Triple) {
   if (Arg *A = Args.getLastArg(options::OPT_mno_omit_leaf_frame_pointer,
                                options::OPT_momit_leaf_frame_pointer))
-    return A->getOption().matches(options::OPT_mno_omit_leaf_frame_pointer);
+    return A->getOption().matches(options::OPT_mno_omit_leaf_frame_pointer) ||
+           mustUseFramePointerForTarget(Triple);
+
   if (Args.hasArg(options::OPT_pg))
     return true;
 
   if (Triple.isPS4CPU())
     return false;
 
-  return shouldUseFramePointerForTarget(Args, Triple);
+  return useFramePointerForTargetByDefault(Args, Triple);
 }
 
 /// Add a CC1 option to specify the debug compilation directory.

diff --git a/test/Driver/frame-pointer-elim.c b/test/Driver/frame-pointer-elim.c
index 139c0ccb952a6d8db0840d4af9338800f983bb24..d2a2715731c3aec3de0164f2b50dc9a2458d204a 100644 (file)
--- a/test/Driver/frame-pointer-elim.c
+++ b/test/Driver/frame-pointer-elim.c
@@ -35,6 +35,24 @@
 // RUN:   FileCheck --check-prefix=OMIT_LEAF %s
 // OMIT_LEAF: "-momit-leaf-frame-pointer"
 
+// 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: "-mdisable-fp-elim"
+// WARN-OMIT-7S-NOT: "-momit-leaf-frame-pointer"
+
+// 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: "-mdisable-fp-elim"
+// WARN-OMIT-7K-NOT: "-momit-leaf-frame-pointer"
+
+// 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: warning: optimization flag '-momit-leaf-frame-pointer' is not supported for target 'armv7s'
+// WARN-OMIT-LEAF-7S: "-mdisable-fp-elim"
+// WARN-OMIT-LEAF-7S-NOT: "-momit-leaf-frame-pointer"
+
 // On the PS4, we default to omitting the frame pointer on leaf functions
 // (OMIT_LEAF check line is above)
 // RUN: %clang -### -target x86_64-scei-ps4 -S %s 2>&1 | \