[SPIRV] Do not emit @llvm.compiler.used (#162678)
`@llvm.compiler.used` holds a series of global values and prevents the compiler from optimizing them out.
However, the symbols in the variable can be optimized after compilation
as usual by a linker (notice that `@llvm.used` instead doesn't allow for
the linker to optimize-out the global variables referenced in it).
This was already done for `@llvm.global.annotations`.
diff --git a/llvm/lib/Target/SPIRV/SPIRVAsmPrinter.cpp b/llvm/lib/Target/SPIRV/SPIRVAsmPrinter.cpp
index b765fec..56a6168 100644
--- a/llvm/lib/Target/SPIRV/SPIRVAsmPrinter.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVAsmPrinter.cpp
@@ -139,8 +139,8 @@
// anymore.
void SPIRVAsmPrinter::cleanUp(Module &M) {
// Verifier disallows uses of intrinsic global variables.
- for (StringRef GVName : {"llvm.global_ctors", "llvm.global_dtors",
- "llvm.used", "llvm.compiler.used"}) {
+ for (StringRef GVName :
+ {"llvm.global_ctors", "llvm.global_dtors", "llvm.used"}) {
if (GlobalVariable *GV = M.getNamedGlobal(GVName))
GV->setName("");
}
diff --git a/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp b/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
index e16c8f0..c6c6182 100644
--- a/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
@@ -17,6 +17,7 @@
#include "SPIRVTargetMachine.h"
#include "SPIRVUtils.h"
#include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/StringSet.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/InstVisitor.h"
@@ -2028,9 +2029,13 @@
void SPIRVEmitIntrinsics::processGlobalValue(GlobalVariable &GV,
IRBuilder<> &B) {
- // Skip special artifical variable llvm.global.annotations.
- if (GV.getName() == "llvm.global.annotations")
+ // Skip special artificial variables.
+ static const StringSet<> ArtificialGlobals{"llvm.global.annotations",
+ "llvm.compiler.used"};
+
+ if (ArtificialGlobals.contains(GV.getName()))
return;
+
Constant *Init = nullptr;
if (hasInitializer(&GV)) {
// Deduce element type and store results in Global Registry.
diff --git a/llvm/test/CodeGen/SPIRV/llvm-compiler-used.ll b/llvm/test/CodeGen/SPIRV/llvm-compiler-used.ll
new file mode 100644
index 0000000..ddc2585
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/llvm-compiler-used.ll
@@ -0,0 +1,19 @@
+; RUN: llc -verify-machineinstrs -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+; RUN: llc -verify-machineinstrs -mtriple=spirv-unknown-vulkan %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -mtriple=spirv-unknown-vulkan %s -o - -filetype=obj | spirv-val %}
+
+; Verify that llvm.compiler.used is not lowered.
+; CHECK: OpName %{{[0-9]+}} "unused"
+; CHECK-NOT: OpName %{{[0-9]+}} "llvm.compiler.used"
+
+; Check that the type of llvm.compiler.used is not emitted too.
+; CHECK-NOT: OpTypeArray
+
+@unused = private addrspace(3) global i32 0
+@llvm.compiler.used = appending addrspace(2) global [1 x ptr addrspace (4)] [ptr addrspace(4) addrspacecast (ptr addrspace(3) @unused to ptr addrspace(4))]
+
+define spir_func void @foo() {
+entry:
+ ret void
+}
