Stop treating -static as overriding -fPIC: they are distinct.

[jyknight]

Summary

For some reason, clang had been treating a command like:
clang -static -fPIC foo.c
as if it should be compiled without the PIC relocation model.

This was incorrect: -static should be affecting only the linking
model, and -fPIC only the compilation.

This new behavior also matches GCC.

This is a follow-up from a review comment on r245447.

[danalbert]

lib/Driver/Tools.cpp

3025

trump-card (singular)

[joerg]

LGTM.

[rnk]

lgtm

[jyknight]

D'oh, I copy/pasted the wrong review link when submitting this. It was submitted as rL245667.

lib/Driver/Tools.cpp

ParsePICArgs(const ToolChain &ToolChain, const llvm::Triple &Triple,
 
   // Introduce a Darwin-specific hack. If the default is PIC, but the
   // PIC level would've been set to level 1, force it back to level 2
   // PIC instead. This matches the behavior of Darwin GCC (based on
   // chandlerc's informal testing in 2012).
   if (PIC && ToolChain.getTriple().isOSDarwin())
     IsPICLevelTwo |= ToolChain.isPICDefault();
 
-  // Note that these flags are trump-cards. Regardless of the order w.r.t. the
-  // PIC or PIE options above, if these show up, PIC is disabled.
+  // Note that this flag is a trump-cards. Regardless of the order
+  // w.r.t. the PIC or PIE options above, if it shows up, PIC is
+  // disabled.
   if (KernelOrKext && (!Triple.isiOS() || Triple.isOSVersionLT(6)))
     PIC = PIE = false;
-  if (Args.hasArg(options::OPT_static))
-    PIC = PIE = false;
 
   if (Arg *A = Args.getLastArg(options::OPT_mdynamic_no_pic)) {
     // This is a very special mode. It trumps the other modes, almost no one
     // uses it, and it isn't even valid on any OS but Darwin.
     if (!ToolChain.getTriple().isOSDarwin())
       ToolChain.getDriver().Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getSpelling() << ToolChain.getTriple().str();
 

test/Driver/pic.c

 // Test the driver's control over the PIC behavior. These consist of tests of
 // the relocation model flags and the pic level flags passed to CC1.
 //
 // CHECK-NO-PIC: "-mrelocation-model" "static"
 // CHECK-NO-PIC-NOT: "-pic-level"
 // CHECK-NO-PIC-NOT: "-pie-level"
 //
 // CHECK-PIC1: "-mrelocation-model" "pic"
 // CHECK-PIC1: "-pic-level" "1"
 //
 // CHECK-PIC2: "-mrelocation-model" "pic"
 // CHECK-PIC2: "-pic-level" "2"
 //
+// CHECK-STATIC: "-static"
 // CHECK-NO-STATIC-NOT: "-static"
 //
 // CHECK-PIE1: "-mrelocation-model" "pic"
 // CHECK-PIE1: "-pic-level" "1"
 // CHECK-PIE1: "-pie-level" "1"
 //
 // CHECK-PIE2: "-mrelocation-model" "pic"
 // CHECK-PIE2: "-pic-level" "2"

 // RUN: %clang %s -target i386-linux-gnu -fPIC -pie -### \
 // RUN: --gcc-toolchain="" \
 // RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIE-LD
 //
 // Disregard any of the PIC-specific flags if we have a trump-card flag.
 // RUN: %clang -c %s -target i386-unknown-unknown -mkernel -fPIC -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
+
+// The -static argument *doesn't* override PIC: -static only affects
+// linking, and -fPIC only affects code generation.
 // RUN: %clang -c %s -target i386-unknown-unknown -static -fPIC -### 2>&1 \
-// RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
+// RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
+// RUN: %clang %s -target i386-linux-gnu -static -fPIC -### \
+// RUN: --gcc-toolchain="" \
+// RUN: --sysroot=%S/Inputs/basic_linux_tree 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-STATIC
 //
 // On Linux, disregard -pie if we have -shared.
 // RUN: %clang %s -target i386-unknown-linux -shared -pie -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIE
 //
 // Darwin is a beautiful and unique snowflake when it comes to these flags.
 // When targeting a 32-bit darwin system, the -fno-* flag variants work and
 // disable PIC, but any other flag enables PIC (*not* PIE) even if the flag

 // RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
 // RUN: %clang -c %s -target arm64-apple-ios -mkernel -miphoneos-version-min=7.0.0 -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
 // RUN: %clang -x assembler -c %s -target arm64-apple-ios -mkernel -miphoneos-version-min=7.0.0 -no-integrated-as -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-STATIC
 // RUN: %clang -c %s -target armv7-apple-ios -fapple-kext -miphoneos-version-min=5.0.0 -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
 // RUN: %clang -c %s -target armv7-apple-ios -fapple-kext -miphoneos-version-min=6.0.0 -static -### 2>&1 \
-// RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
+// RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
 //
 // On OpenBSD, PIE is enabled by default, but can be disabled.
 // RUN: %clang -c %s -target amd64-pc-openbsd -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIE1
 // RUN: %clang -c %s -target i386-pc-openbsd -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIE1
 // RUN: %clang -c %s -target mips64-unknown-openbsd -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIE1