[clang][Driver][HIP] Change OffloadingActionBuilder to respect the --no-gpu-bundle-output flag

[MixedMatched]

Currently, the command clang -c -emit-llvm --no-gpu-bundle-output --offload-arch=gfx900,gfx1030 -O3 -x hip square.hip will lead to a bundled output:

❯ ../bin/clang -c -emit-llvm --no-gpu-bundle-output --offload-arch=gfx900,gfx1030 -O3 -x hip square.hip
❯ ls
square.hip
square.bc

This doesn't match my expectation of the behavior of --no-gpu-bundle-output, so this adds a check into OffloadingActionBuilder for the flag when replacing the host compile action for a bundling action.

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[llvmbot]

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: alessandra simmons (MixedMatched)

Changes

Currently, the command clang -c -emit-llvm --no-gpu-bundle-output --offload-arch=gfx900,gfx1030 -O3 -x hip square.hip will lead to a bundled output:

❯ ../bin/clang -c -emit-llvm --no-gpu-bundle-output --offload-arch=gfx900,gfx1030 -O3 -x hip square.hip
❯ ls
square.hip
square.bc

This doesn't match my expectation of the behavior of --no-gpu-bundle-output, so this adds a check into OffloadingActionBuilder for the flag when replacing the host compile action for a bundling action.

---

Full diff: https://github.com/llvm/llvm-project/pull/163834.diff

2 Files Affected:

• (modified) clang/lib/Driver/Driver.cpp (+11-5)
• (added) clang/test/Driver/no-gpu-bundle-respected.hip (+18)

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 40ea513e85427..02cfc4314bbc4 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -3844,6 +3844,9 @@ class OffloadingActionBuilder final {
   /// Flag set to true if all valid builders allow file bundling/unbundling.
   bool CanUseBundler;
 
+  /// Flag set to false if an argument turns off bundling.
+  bool ShouldUseBundler;
+
 public:
   OffloadingActionBuilder(Compilation &C, DerivedArgList &Args,
                           const Driver::InputList &Inputs)
@@ -3878,6 +3881,9 @@ class OffloadingActionBuilder final {
     }
     CanUseBundler =
         ValidBuilders && ValidBuilders == ValidBuildersSupportingBundling;
+
+    ShouldUseBundler = Args.hasFlag(options::OPT_gpu_bundle_output,
+                                    options::OPT_no_gpu_bundle_output, true);
   }
 
   ~OffloadingActionBuilder() {
@@ -4029,11 +4035,11 @@ class OffloadingActionBuilder final {
       SB->appendTopLevelActions(OffloadAL);
     }
 
-    // If we can use the bundler, replace the host action by the bundling one in
-    // the resulting list. Otherwise, just append the device actions. For
-    // device only compilation, HostAction is a null pointer, therefore only do
-    // this when HostAction is not a null pointer.
-    if (CanUseBundler && HostAction &&
+    // If we can and should use the bundler, replace the host action by the
+    // bundling one in the resulting list. Otherwise, just append the device
+    // actions. For device only compilation, HostAction is a null pointer,
+    // therefore only do this when HostAction is not a null pointer.
+    if (CanUseBundler && ShouldUseBundler && HostAction &&
         HostAction->getType() != types::TY_Nothing && !OffloadAL.empty()) {
       // Add the host action to the list in order to create the bundling action.
       OffloadAL.push_back(HostAction);
diff --git a/clang/test/Driver/no-gpu-bundle-respected.hip b/clang/test/Driver/no-gpu-bundle-respected.hip
new file mode 100644
index 0000000000000..1587551f0322d
--- /dev/null
+++ b/clang/test/Driver/no-gpu-bundle-respected.hip
@@ -0,0 +1,18 @@
+// RUN: %clang -ccc-print-phases -c -emit-llvm \
+// RUN:   --offload-arch=gfx900,gfx1030 -O3 -x hip %s \
+// RUN:   2>&1 | FileCheck %s --check-prefix=OFFLOAD
+
+// RUN: %clang -ccc-print-phases -c -emit-llvm \
+// RUN:   --gpu-bundle-output --offload-arch=gfx900,gfx1030 -O3 -x hip %s \
+// RUN:   2>&1 | FileCheck %s --check-prefix=OFFLOAD
+
+// RUN: %clang -ccc-print-phases -c -emit-llvm \
+// RUN:   --no-gpu-bundle-output --offload-arch=gfx900,gfx1030 -O3 -x hip %s \
+// RUN:   2>&1 | FileCheck %s --check-prefix=OFFLOAD2
+
+// OFFLOAD: clang-offload-bundler
+// OFFLOAD2-NOT: clang-offload-bundler
+
+int square(int num) {
+    return num * num;
+}

[MixedMatched]

@lamb-j @yxsamliu

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[lamb-j]

lgtm, seems reasonable to not unbundle when --no-gpu-bundle-output is specified

Can you wait a day or two before landing to see if any other reviewer has feedback? Thanks!

[yxsamliu]

use a meaningful check line, e.g. BUNDLE, NOBUNDLE. also check the action entries for the NOBUNDLE case.