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new 42a534996c [Target][LLVM] Fix -mcpu validation compatibility across
LLVM versions (#18909)
42a534996c is described below
commit 42a534996cce3ac76d44c75c23af595190eae450
Author: Shushi Hong <[email protected]>
AuthorDate: Wed Mar 18 13:56:09 2026 -0400
[Target][LLVM] Fix -mcpu validation compatibility across LLVM versions
(#18909)
PR #18884 replaced the `getAllProcessorDescriptions()` enumeration check
with `MCSubtargetInfo::isCPUStringValid()` to fix LLVM 22+ where
`apple-m1` became an alias not listed in the enumeration. However, on
LLVM 19, `isCPUStringValid("apple-m1")` returns false, even though the
CPU is valid and present in the enumeration, producing errors like:
```
Error: Using LLVM 19.1.7
with `-mcpu=apple-m1` is not valid in `-mtriple=arm64-apple-macos`, using
default `-mcpu=generic`
[20:03:31] /workspace/tvm/src/target/llvm/llvm_instance.cc:219: Error:
Using LLVM 19.1.7 with
`-mcpu=apple-m1` is not valid in `-mtriple=arm64-apple-macos`, using
default `-mcpu=generic`
[20:03:31] /workspace/tvm/src/target/llvm/llvm_instance.cc:219: Error:
Using LLVM 19.1.7 with
`-mcpu=apple-m2` is not valid in `-mtriple=arm64-apple-macos`, using
default `-mcpu=generic`
[20:03:31] /workspace/tvm/src/target/llvm/llvm_instance.cc:219: Error:
Using LLVM 19.1.7 with
`-mcpu=apple-m2` is not valid in `-mtriple=arm64-apple-macos`, using
default `-mcpu=generic`
[20:03:31] /workspace/tvm/src/target/llvm/llvm_instance.cc:219: Error:
Using LLVM 19.1.7 with
`-mcpu=apple-m1` is not valid in `-mtriple=arm64-apple-macos`, using
default `-mcpu=generic`
[20:03:31] /workspace/tvm/src/target/llvm/llvm_instance.cc:219: Error:
Using LLVM 19.1.7 with
`-mcpu=apple-m1` is not valid in `-mtriple=arm64-apple-macos`, using
default `-mcpu=generic`
```
- Fix `-mcpu` validation regression introduced by #18884, where
`isCPUStringValid()` returns false for valid CPUs like `apple-m1` on
LLVM 19, causing spurious `LOG(ERROR)` warnings
- Take the union of both validation methods: try `isCPUStringValid()`
first (handles LLVM 22+ aliases), then fall back to
`getAllProcessorDescriptions()` enumeration (handles LLVM 17-21)
---
src/target/llvm/llvm_instance.cc | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/src/target/llvm/llvm_instance.cc b/src/target/llvm/llvm_instance.cc
index 90d3b65966..0e2c82b15a 100644
--- a/src/target/llvm/llvm_instance.cc
+++ b/src/target/llvm/llvm_instance.cc
@@ -443,8 +443,7 @@ llvm::TargetMachine*
LLVMTargetInfo::GetOrCreateTargetMachine(bool allow_missing
bool LLVMTargetInfo::IsValidCPU(const std::string& cpu) const {
auto llvm_instance = CreateLLVMTargetInstance(triple_, true);
if (!llvm_instance) return false;
- // Create MCSubtargetInfo directly instead of a full TargetMachine,
- // since we only need isCPUStringValid which correctly handles CPU aliases
+ // Use isCPUStringValid which correctly handles CPU aliases
// (e.g. apple-m1 in LLVM 22+) that don't appear in
getAllProcessorDescriptions().
#if TVM_LLVM_VERSION >= 220
llvm::Triple triple_obj(triple_);
@@ -454,7 +453,22 @@ bool LLVMTargetInfo::IsValidCPU(const std::string& cpu)
const {
std::unique_ptr<llvm::MCSubtargetInfo> mc_info(
llvm_instance->createMCSubtargetInfo(triple_, "", ""));
#endif
- return mc_info && mc_info->isCPUStringValid(cpu);
+ if (mc_info && mc_info->isCPUStringValid(cpu)) {
+ return true;
+ }
+ // Fallback: on older LLVM versions (e.g. 19), isCPUStringValid may not
+ // recognize valid CPUs like apple-m1 that do appear in the processor
+ // enumeration. Check getAllProcessorDescriptions as a fallback.
+ if (mc_info) {
+#if TVM_LLVM_VERSION >= 170
+ for (const auto& desc : mc_info->getAllProcessorDescriptions()) {
+ if (cpu == desc.Key) {
+ return true;
+ }
+ }
+#endif
+ }
+ return false;
}
std::string LLVMTargetInfo::GetTargetFeatureString() const { //
