[llvm] [SPIR-V] Ensure that internal intrinsic functions for PHI's operand are inserted at the correct positions (PR #92316)

[Vyacheslav Levytskyy via llvm-commits]

https://github.com/VyacheslavLevytskyy created https://github.com/llvm/llvm-project/pull/92316

This PR is to ensure that internal intrinsic functions for PHI's operand are inserted at the correct positions and don't break rules of instruction domination and PHI nodes grouping at top of basic block.

>From b2abf70ca29bad96a56dbb56bafd3c1a1670c33c Mon Sep 17 00:00:00 2001
From: "Levytskyy, Vyacheslav" <vyacheslav.levytskyy at intel.com>
Date: Wed, 15 May 2024 13:53:48 -0700
Subject: [PATCH] internal intrinsic functions for PHI's operand are inserted
 at the correct positions

---
 llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp |  4 +-
 llvm/test/CodeGen/SPIRV/phi-insert-point.ll   | 59 +++++++++++++++++++
 2 files changed, 61 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/CodeGen/SPIRV/phi-insert-point.ll

diff --git a/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp b/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
index c00066f5dca62..d90249f7c2e63 100644
--- a/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
+++ b/llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp
@@ -174,7 +174,7 @@ static bool isAggrToReplace(const Value *V) {
 
 static void setInsertPointSkippingPhis(IRBuilder<> &B, Instruction *I) {
   if (isa<PHINode>(I))
-    B.SetInsertPoint(I->getParent(), I->getParent()->getFirstInsertionPt());
+    B.SetInsertPoint(I->getParent()->getFirstNonPHIOrDbgOrAlloca());
   else
     B.SetInsertPoint(I);
 }
@@ -491,7 +491,7 @@ void SPIRVEmitIntrinsics::deduceOperandElementType(Instruction *I) {
     if (Instruction *User = dyn_cast<Instruction>(Op->use_begin()->get()))
       setInsertPointSkippingPhis(B, User->getNextNode());
     else
-      B.SetInsertPoint(I);
+      setInsertPointSkippingPhis(B, I);
     Value *OpTyVal = Constant::getNullValue(KnownElemTy);
     Type *OpTy = Op->getType();
     if (!Ty) {
diff --git a/llvm/test/CodeGen/SPIRV/phi-insert-point.ll b/llvm/test/CodeGen/SPIRV/phi-insert-point.ll
new file mode 100644
index 0000000000000..41cc514f4dbae
--- /dev/null
+++ b/llvm/test/CodeGen/SPIRV/phi-insert-point.ll
@@ -0,0 +1,59 @@
+; The goal of the test is to check that internal intrinsic functions for PHI's
+; operand are inserted at the correct positions, and don't break rules of
+; instruction domination and PHI nodes grouping at top of basic block.
+
+; RUN: llc -O0 -mtriple=spirv64-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv64-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; CHECK-DAG: OpName %[[#Foo:]] "foo"
+; CHECK-DAG: OpName %[[#Bar:]] "bar"
+; CHECK: %[[#Foo]] = OpFunction
+; CHECK: OpPhi
+; CHECK-NEXT: OpPhi
+; CHECK-NEXT: OpPhi
+; CHECK-NEXT: OpPhi
+; CHECK: %[[#Bar]] = OpFunction
+; CHECK: OpPhi
+; CHECK-NEXT: OpPhi
+; CHECK-NEXT: OpPhi
+; CHECK-NEXT: OpPhi
+
+%struct = type { i64, i64 }
+
+define spir_kernel void @foo(i64 %arg_val, ptr addrspace(4) byval(%struct) %arg_ptr) {
+entry:
+  %fl = icmp eq i64 %arg_val, 0
+  br i1 %fl, label %ok, label %err
+
+err:
+  br label %ok
+
+ok:
+  %r1 = phi i64 [ undef, %err ], [ %arg_val, %entry ]
+  %r2 = phi i64 [ undef, %err ], [ %arg_val, %entry ]
+  %r3 = phi ptr addrspace(4) [ undef, %err ], [ %arg_ptr, %entry ]
+  %r4 = phi ptr addrspace(4) [ undef, %err ], [ %arg_ptr, %entry ]
+  br label %exit
+
+exit:
+  ret void
+}
+
+define spir_kernel void @bar(i64 %arg_val, i64 %arg_val_def, ptr addrspace(4) byval(%struct) %arg_ptr, ptr addrspace(4) %arg_ptr_def) {
+entry:
+  %fl = icmp eq i64 %arg_val, 0
+  br i1 %fl, label %ok, label %err
+
+err:
+  br label %ok
+
+ok:
+  %r1 = phi i64 [ %arg_val_def, %err ], [ %arg_val, %entry ]
+  %r2 = phi i64 [ %arg_val_def, %err ], [ %arg_val, %entry ]
+  %r3 = phi ptr addrspace(4) [ %arg_ptr_def, %err ], [ %arg_ptr, %entry ]
+  %r4 = phi ptr addrspace(4) [ %arg_ptr_def, %err ], [ %arg_ptr, %entry ]
+  br label %exit
+
+exit:
+  ret void
+}