[llvm] [SPIR-V] Look up printf format string type in the correct function (PR #201523)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-spir-v

Author: Tim Besard (maleadt)

<details>
<summary>Changes</summary>

addPrintfRequirements() resolved the SPIR-V type of the format string operand via getSPIRVTypeForVReg() without passing the instruction's parent MachineFunction, so the lookup defaulted to the registry's CurMF: whichever function happened to be processed last. Virtual register numbers are only unique within a function, so in multi-function modules the check could inspect an unrelated function's type. A colliding vreg with a non-UniformConstant pointer type triggered a spurious fatal "SPV_EXT_relaxed_printf_string_address_space is required" error even when the format string was in the constant address space; conversely, the extension requirement could be silently skipped when the colliding vreg had no recorded type.

---
Full diff: https://github.com/llvm/llvm-project/pull/201523.diff


2 Files Affected:

- (modified) llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp (+2-1) 
- (added) llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_relaxed_printf_string_address_space/multi-function-printf.ll (+40) 


``````````diff
diff --git a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
index 49d9dc95603ca..8294aa4b45ea2 100644
--- a/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVModuleAnalysis.cpp
@@ -1478,7 +1478,8 @@ void addPrintfRequirements(const MachineInstr &MI,
                            SPIRV::RequirementHandler &Reqs,
                            const SPIRVSubtarget &ST) {
   SPIRVGlobalRegistry *GR = ST.getSPIRVGlobalRegistry();
-  SPIRVTypeInst PtrType = GR->getSPIRVTypeForVReg(MI.getOperand(4).getReg());
+  SPIRVTypeInst PtrType =
+      GR->getSPIRVTypeForVReg(MI.getOperand(4).getReg(), MI.getMF());
   if (PtrType) {
     MachineOperand ASOp = PtrType->getOperand(1);
     if (ASOp.isImm()) {
diff --git a/llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_relaxed_printf_string_address_space/multi-function-printf.ll b/llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_relaxed_printf_string_address_space/multi-function-printf.ll
new file mode 100644
index 0000000000000..ec0aead14b867
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/extensions/SPV_EXT_relaxed_printf_string_address_space/multi-function-printf.ll
@@ -0,0 +1,40 @@
+; RUN: llc -O0 -mtriple=spirv64-unknown-unknown %s -o - | FileCheck %s
+
+; The format string is in the constant address space, so no extension is
+; required. The pointer type of the format string used to be looked up in
+; whichever function was processed last instead of the calling function,
+; spuriously requiring the extension when an unrelated function's colliding
+; virtual register had a non-UniformConstant pointer type.
+
+; CHECK: OpExtInstImport "OpenCL.std"
+; CHECK-NOT: OpExtension "SPV_EXT_relaxed_printf_string_address_space"
+
+ at .str = private unnamed_addr addrspace(2) constant [6 x i8] c"hello\00", align 1
+
+declare i32 @printf(ptr addrspace(2), ...)
+
+define spir_kernel void @kern() {
+top:
+  %r = call i32 (ptr addrspace(2), ...) @printf(ptr addrspace(2) @.str)
+  ret void
+}
+
+define void @tail(ptr addrspace(3) %p) {
+top:
+  %g1 = getelementptr inbounds i32, ptr addrspace(3) %p, i64 1
+  %v1 = load i32, ptr addrspace(3) %g1, align 4
+  %g2 = getelementptr inbounds i32, ptr addrspace(3) %p, i64 2
+  %v2 = load i32, ptr addrspace(3) %g2, align 4
+  %g3 = getelementptr inbounds i32, ptr addrspace(3) %p, i64 3
+  %v3 = load i32, ptr addrspace(3) %g3, align 4
+  %g4 = getelementptr inbounds i32, ptr addrspace(3) %p, i64 4
+  %v4 = load i32, ptr addrspace(3) %g4, align 4
+  %g5 = getelementptr inbounds i32, ptr addrspace(3) %p, i64 5
+  %v5 = load i32, ptr addrspace(3) %g5, align 4
+  %s1 = add i32 %v1, %v2
+  %s2 = add i32 %s1, %v3
+  %s3 = add i32 %s2, %v4
+  %s4 = add i32 %s3, %v5
+  store i32 %s4, ptr addrspace(3) %p, align 4
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/201523