[clang] 070acb1 - [Driver][ARM] parse version of arm/thumb architecture correctly

[Daniel Kiss via cfe-commits]

Author: Daniel Kiss
Date: 2020-07-01T12:13:52+02:00
New Revision: 070acb1d1e51ffd289a46b8f93e993635d0053b7

URL: https://github.com/llvm/llvm-project/commit/070acb1d1e51ffd289a46b8f93e993635d0053b7
DIFF: https://github.com/llvm/llvm-project/commit/070acb1d1e51ffd289a46b8f93e993635d0053b7.diff

LOG: [Driver][ARM] parse version of arm/thumb architecture correctly

Summary:
If you execute the following commandline multiple times, the behavior was not always the same:
  clang++ --target=thumbv7em-none-windows-eabi-coff -march=armv7-m -mcpu=cortex-m7 -o temp.obj -c -x c++ empty.cpp

Most of the time the compilation succeeded, but sometimes clang reported this error:
  clang++: error: the target architecture 'thumbv7em' is not supported by the target 'thumbv7em-none-windows-eabi'

The cause of the inconsistent behavior was the uninitialized variable Version.

With these commandline arguments, the variable Version was not set by getAsInteger(),
because it cannot parse a number from the substring "7em" (of "thumbv7em").
To get a consistent behaviour, it's enough to initialize the variable Version to zero.
Zero is smaller than 7, so the comparison will be true.
Then the command always fails with the error message seen above.

By using consumeInteger() instead of getAsInteger() we get 7 from the substring "7em"
and the command does not fail.

Reviewers: compnerd, danielkiss

Reviewed By: danielkiss

Subscribers: danielkiss, kristof.beyls, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D75453

Added: 
    clang/test/Driver/windows-thumbv7em.cpp

Modified: 
    clang/lib/Driver/ToolChains/Clang.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 9db6bbadf566..a2cc84805c9c 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4041,9 +4041,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (Triple.isOSWindows() && (Triple.getArch() == llvm::Triple::arm ||
                                Triple.getArch() == llvm::Triple::thumb)) {
     unsigned Offset = Triple.getArch() == llvm::Triple::arm ? 4 : 6;
-    unsigned Version;
-    Triple.getArchName().substr(Offset).getAsInteger(10, Version);
-    if (Version < 7)
+    unsigned Version = 0;
+    bool Failure =
+        Triple.getArchName().substr(Offset).consumeInteger(10, Version);
+    if (Failure || Version < 7)
       D.Diag(diag::err_target_unsupported_arch) << Triple.getArchName()
                                                 << TripleStr;
   }

diff  --git a/clang/test/Driver/windows-thumbv7em.cpp b/clang/test/Driver/windows-thumbv7em.cpp
new file mode 100644
index 000000000000..5d7c00b31fd1
--- /dev/null
+++ b/clang/test/Driver/windows-thumbv7em.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang -target thumb-none-windows-eabi-coff -mcpu=cortex-m7 -### -c %s 2>&1 \
+// RUN: | FileCheck %s --check-prefix CHECK-V7
+// CHECK-V7-NOT: error: the target architecture 'thumbv7em' is not supported by the target 'thumbv7em-none-windows-eabi'
+
+// RUN: %clang -target thumb-none-windows-eabi-coff -mcpu=cortex-m1 -### -c %s 2>&1 \
+// RUN: | FileCheck %s --check-prefix CHECK-V6
+// CHECK-V6: error: the target architecture 'thumbv6m' is not supported by the target 'thumbv6m-none-windows-eabi'
+