[Clang][Driver] Disable llvm passes for the first host OpenMP offload compilation

[sdmitriev]

Summary

With OpenMP offloading host compilation is done in two phases to capture host IR that is passed to all device compilations as input. But it turns out that we currently run entire LLVM optimization pipeline on host IR on both compilations which may have unpredictable effects on the resulting code. This patch fixes this problem by disabling LLVM passes on the first compilation, so the host IR that is passed to device compilations will be captured right after front end.

[ABataev]

LG

clang/lib/Driver/ToolChains/Clang.cpp

   // With -save-temps, we want to save the unoptimized bitcode output from the
   // CompileJobAction, use -disable-llvm-passes to get pristine IR generated
   // by the frontend.
   // When -fembed-bitcode is enabled, optimized bitcode is emitted because it
   // has slightly different breakdown between stages.
   // FIXME: -fembed-bitcode -save-temps will save optimized bitcode instead of
   // pristine IR generated by the frontend. Ideally, a new compile action should
   // be added so both IR can be captured.
-  if (C.getDriver().isSaveTempsEnabled() &&
+  if ((C.getDriver().isSaveTempsEnabled() ||
+       JA.isHostOffloading(Action::OFK_OpenMP)) &&
       !(C.getDriver().embedBitcodeInObject() && !C.getDriver().isUsingLTO()) &&
       isa<CompileJobAction>(JA))
     CmdArgs.push_back("-disable-llvm-passes");
 
   Args.AddAllArgs(CmdArgs, options::OPT_undef);
 
   const char *Exec = D.getClangProgramPath();
 

clang/test/Driver/openmp-offload.c

 // RUN:   %clang -### -fopenmp=libomp -o %t.out -target powerpc64le-linux -fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu %s -no-canonical-prefixes 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHK-COMMANDS %s
 // RUN:   %clang -### -fopenmp=libomp -o %t.out -target powerpc64le-linux -fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu %s -save-temps -no-canonical-prefixes 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHK-COMMANDS-ST %s
 
 //
 // Generate host BC file and host object.
 //
-// CHK-COMMANDS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"
+// CHK-COMMANDS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-disable-llvm-passes"
 // CHK-COMMANDS-SAME: "-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu"
 // CHK-COMMANDS-SAME: "-o" "
 // CHK-COMMANDS-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "c" "
 // CHK-COMMANDS-SAME: [[INPUT:[^\\/]+\.c]]"
 // CHK-COMMANDS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-obj" {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-COMMANDS-SAME: [[HOSTOBJ:[^\\/]+\.o]]" "-x" "ir" "{{.*}}[[HOSTBC]]"
 // CHK-COMMANDS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-E" {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-COMMANDS-ST-SAME: [[HOSTPP:[^\\/]+\.i]]" "-x" "c" "
 // CHK-COMMANDS-ST-SAME: [[INPUT:[^\\/]+\.c]]"
-// CHK-COMMANDS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-COMMANDS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-COMMANDS-ST-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[HOSTPP]]"
 // CHK-COMMANDS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-S" {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-COMMANDS-ST-SAME: [[HOSTASM:[^\\/]+\.s]]" "-x" "ir" "{{.*}}[[HOSTBC]]"
 // CHK-COMMANDS-ST: clang{{.*}}" "-cc1as" "-triple" "powerpc64le-unknown-linux" "-filetype" "obj" {{.*}}"-o" "
 // CHK-COMMANDS-ST-SAME: [[HOSTOBJ:[^\\/]+\.o]]" "{{.*}}[[HOSTASM]]"
 
 //
 // Compile for the powerpc device.

 
 /// Check separate compilation with offloading - bundling jobs construct
 // RUN:   %clang -### -fopenmp=libomp -c -o %t.o -lsomelib -target powerpc64le-linux -fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu %s -no-canonical-prefixes 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHK-BUJOBS %s
 // RUN:   %clang -### -fopenmp=libomp -c -o %t.o -lsomelib -target powerpc64le-linux -fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu %s -save-temps -no-canonical-prefixes 2>&1 \
 // RUN:   | FileCheck -check-prefix=CHK-BUJOBS-ST %s
 
 // Create host BC.
-// CHK-BUJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"  {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-BUJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-BUJOBS-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "c" "
 // CHK-BUJOBS-SAME: [[INPUT:[^\\/]+\.c]]"
 
 // CHK-BUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-E"  {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-BUJOBS-ST-SAME: [[HOSTPP:[^\\/]+\.i]]" "-x" "c" "
 // CHK-BUJOBS-ST-SAME: [[INPUT:[^\\/]+\.c]]"
-// CHK-BUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"  {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-BUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-BUJOBS-ST-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[HOSTPP]]"
 
 // Create target 1 object.
 // CHK-BUJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-obj" {{.*}}"-fopenmp" {{.*}}"-fopenmp-is-device" "-fopenmp-host-ir-file-path" "{{.*}}[[HOSTBC]]" {{.*}}"-o" "
 // CHK-BUJOBS-SAME: [[T1OBJ:[^\\/]+\.o]]" "-x" "c" "{{.*}}[[INPUT]]"
 // CHK-BUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-E" {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-BUJOBS-ST-SAME: [[T1PP:[^\\/]+\.i]]" "-x" "c" "{{.*}}[[INPUT]]"
 // CHK-BUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-fopenmp-is-device" "-fopenmp-host-ir-file-path" "{{.*}}[[HOSTBC]]" {{.*}}"-o" "

 // RUN:   | FileCheck -check-prefix=CHK-UBJOBS2-ST %s
 
 // Unbundle and create host BC.
 // CHK-UBJOBS: clang-offload-bundler{{.*}}" "-type=i" "-targets=host-powerpc64le-unknown-linux,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu" "-inputs=
 // CHK-UBJOBS-SAME: [[INPUT:[^\\/]+\.i]]" "-outputs=
 // CHK-UBJOBS-SAME: [[HOSTPP:[^\\/]+\.i]],
 // CHK-UBJOBS-SAME: [[T1PP:[^\\/]+\.i]],
 // CHK-UBJOBS-SAME: [[T2PP:[^\\/]+\.i]]" "-unbundle"
-// CHK-UBJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"  {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-UBJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-UBJOBS-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[HOSTPP]]"
 // CHK-UBJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-obj" {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-UBJOBS-SAME: [[HOSTOBJ:[^\\/]+\.o]]" "-x" "ir" "{{.*}}[[HOSTBC]]"
 // CHK-UBJOBS-ST: clang-offload-bundler{{.*}}" "-type=i" "-targets=host-powerpc64le-unknown-linux,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu" "-inputs=
 // CHK-UBJOBS-ST-SAME: [[INPUT:[^\\/]+\.i]]" "-outputs=
 // CHK-UBJOBS-ST-SAME: [[HOSTPP:[^\\/,]+\.i]],
 // CHK-UBJOBS-ST-SAME: [[T1PP:[^\\/,]+\.i]],
 // CHK-UBJOBS-ST-SAME: [[T2PP:[^\\/,]+\.i]]" "-unbundle"
-// CHK-UBJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"  {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-UBJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-UBJOBS-ST-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[HOSTPP]]"
 // CHK-UBJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-S" {{.*}}"-fopenmp" {{.*}}"-o" "
 // CHK-UBJOBS-ST-SAME: [[HOSTASM:[^\\/]+\.s]]" "-x" "ir" "{{.*}}[[HOSTBC]]"
 // CHK-UBJOBS-ST: clang{{.*}}" "-cc1as" "-triple" "powerpc64le-unknown-linux" "-filetype" "obj" {{.*}}"-o" "
 // CHK-UBJOBS-ST-SAME: [[HOSTOBJ:[^\\/]+\.o]]" "{{.*}}[[HOSTASM]]"
 
 // Create target 1 object.
 // CHK-UBJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-obj" {{.*}}"-fopenmp" {{.*}}"-fopenmp-is-device" "-fopenmp-host-ir-file-path" "{{.*}}[[HOSTBC]]" {{.*}}"-o" "

 // RUN:   | FileCheck -check-prefix=CHK-UBUJOBS-ST %s
 
 // Unbundle and create host BC.
 // CHK-UBUJOBS: clang-offload-bundler{{.*}}" "-type=i" "-targets=host-powerpc64le-unknown-linux,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu" "-inputs=
 // CHK-UBUJOBS-SAME: [[INPUT:[^\\/]+\.i]]" "-outputs=
 // CHK-UBUJOBS-SAME: [[HOSTPP:[^\\/]+\.i]],
 // CHK-UBUJOBS-SAME: [[T1PP:[^\\/]+\.i]],
 // CHK-UBUJOBS-SAME: [[T2PP:[^\\/]+\.i]]" "-unbundle"
-// CHK-UBUJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"  {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-UBUJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-UBUJOBS-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[HOSTPP]]"
 
 // CHK-UBUJOBS-ST: clang-offload-bundler{{.*}}" "-type=i" "-targets=host-powerpc64le-unknown-linux,openmp-powerpc64le-ibm-linux-gnu,openmp-x86_64-pc-linux-gnu" "-inputs=
 // CHK-UBUJOBS-ST-SAME: [[INPUT:[^\\/]+\.i]]" "-outputs=
 // CHK-UBUJOBS-ST-SAME: [[HOSTPP:[^\\/,]+\.i]],
 // CHK-UBUJOBS-ST-SAME: [[T1PP:[^\\/,]+\.i]],
 // CHK-UBUJOBS-ST-SAME: [[T2PP:[^\\/,]+\.i]]" "-unbundle"
-// CHK-UBUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc"  {{.*}}"-fopenmp" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
+// CHK-UBUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-disable-llvm-passes" {{.*}}"-fopenmp-targets=powerpc64le-ibm-linux-gnu,x86_64-pc-linux-gnu" {{.*}}"-o" "
 // CHK-UBUJOBS-ST-SAME: [[HOSTBC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[HOSTPP]]"
 
 // Create target 1 object.
 // CHK-UBUJOBS: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-obj" {{.*}}"-fopenmp" {{.*}}"-fopenmp-is-device" "-fopenmp-host-ir-file-path" "{{.*}}[[HOSTBC]]" {{.*}}"-o" "
 // CHK-UBUJOBS-SAME: [[T1OBJ:[^\\/]+\.o]]" "-x" "cpp-output" "{{.*}}[[T1PP]]"
 // CHK-UBUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-emit-llvm-bc" {{.*}}"-fopenmp" {{.*}}"-fopenmp-is-device" "-fopenmp-host-ir-file-path" "{{.*}}[[HOSTBC]]" {{.*}}"-o" "
 // CHK-UBUJOBS-ST-SAME: [[T1BC:[^\\/]+\.bc]]" "-x" "cpp-output" "{{.*}}[[T1PP]]"
 // CHK-UBUJOBS-ST: clang{{.*}}" "-cc1" "-triple" "powerpc64le-ibm-linux-gnu" "-aux-triple" "powerpc64le-unknown-linux" {{.*}}"-S" {{.*}}"-fopenmp" {{.*}}"-o" "