commit 6b6d3447317673015f62206b2669c2d0a74132dc
Author: Daniel Kiss <daniel.kiss@arm.com>
Date:   Wed Aug 11 10:11:31 2021 +0200

    [libunwind] Compile with -Wunused-but-set-variable
    
    -Wunused-but-set-variable triggers a warning even the block of code is effectively dead.
    
    Reviewed By: MaskRay
    
    Differential Revision: https://reviews.llvm.org/D107835

diff --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
index b1ef11bf7327..a73f5b0c7bdf 100644
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -191,6 +191,7 @@ add_compile_flags_if_supported(-Wsign-compare)
 add_compile_flags_if_supported(-Wsign-conversion)
 add_compile_flags_if_supported(-Wstrict-aliasing=2)
 add_compile_flags_if_supported(-Wstrict-overflow=4)
+add_compile_flags_if_supported(-Wunused-but-set-variable)
 add_compile_flags_if_supported(-Wunused-parameter)
 add_compile_flags_if_supported(-Wunused-variable)
 add_compile_flags_if_supported(-Wwrite-strings)
diff --git a/libunwind/src/Unwind-EHABI.cpp b/libunwind/src/Unwind-EHABI.cpp
index ba6064d3ef00..a564fd5240dd 100644
--- a/libunwind/src/Unwind-EHABI.cpp
+++ b/libunwind/src/Unwind-EHABI.cpp
@@ -463,6 +463,7 @@ unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
       return _URC_FATAL_PHASE1_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -481,6 +482,7 @@ unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
           frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
+#endif
 
     // If there is a personality routine, ask it if it will want to stop at
     // this frame.
@@ -582,6 +584,7 @@ static _Unwind_Reason_Code unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor
       return _URC_FATAL_PHASE2_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -598,6 +601,7 @@ static _Unwind_Reason_Code unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor
           functionName, sp, frameInfo.lsda,
           frameInfo.handler);
     }
+#endif
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
@@ -689,6 +693,7 @@ unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
       return _URC_FATAL_PHASE2_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -704,6 +709,7 @@ unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
           (void *)exception_object, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
+#endif
 
     // Call stop function at each frame.
     _Unwind_Action action =
diff --git a/libunwind/src/Unwind-seh.cpp b/libunwind/src/Unwind-seh.cpp
index 6e2b4e73e41e..5a6a719730c8 100644
--- a/libunwind/src/Unwind-seh.cpp
+++ b/libunwind/src/Unwind-seh.cpp
@@ -244,6 +244,7 @@ unwind_phase2_forced(unw_context_t *uc,
       return _URC_FATAL_PHASE2_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -259,6 +260,7 @@ unwind_phase2_forced(unw_context_t *uc,
           (void *)exception_object, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
+#endif
 
     // Call stop function at each frame.
     _Unwind_Action action =
diff --git a/libunwind/src/UnwindLevel1.c b/libunwind/src/UnwindLevel1.c
index 68e5e48b8c05..8b8797fb88ad 100644
--- a/libunwind/src/UnwindLevel1.c
+++ b/libunwind/src/UnwindLevel1.c
@@ -68,6 +68,7 @@ unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
       return _URC_FATAL_PHASE1_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -85,6 +86,7 @@ unwind_phase1(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
           (void *)exception_object, pc, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
+#endif
 
     // If there is a personality routine, ask it if it will want to stop at
     // this frame.
@@ -167,6 +169,7 @@ unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
       return _URC_FATAL_PHASE2_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -183,6 +186,7 @@ unwind_phase2(unw_context_t *uc, unw_cursor_t *cursor, _Unwind_Exception *except
                                  functionName, sp, frameInfo.lsda,
                                  frameInfo.handler);
     }
+#endif
 
     // If there is a personality routine, tell it we are unwinding.
     if (frameInfo.handler != 0) {
@@ -258,6 +262,7 @@ unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
       return _URC_FATAL_PHASE2_ERROR;
     }
 
+#ifndef NDEBUG
     // When tracing, print state information.
     if (_LIBUNWIND_TRACING_UNWINDING) {
       char functionBuf[512];
@@ -273,6 +278,7 @@ unwind_phase2_forced(unw_context_t *uc, unw_cursor_t *cursor,
           (void *)exception_object, frameInfo.start_ip, functionName,
           frameInfo.lsda, frameInfo.handler);
     }
+#endif
 
     // Call stop function at each frame.
     _Unwind_Action action =