[PATCH] D97108: [Statepoint Lowering] Allow dead gc pointer from deopt section to be on register.

[Serguei Katkov via Phabricator via llvm-commits]

skatkov updated this revision to Diff 325171.
skatkov added a comment.

ok, if we do not need to limit deopt gc values then I decided to return back almost to what you reverted.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D97108/new/

https://reviews.llvm.org/D97108

Files:
  llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
  llvm/test/CodeGen/X86/statepoint-vreg-dead-gc-deopt.ll
  llvm/test/CodeGen/X86/statepoint-vreg-details.ll


Index: llvm/test/CodeGen/X86/statepoint-vreg-details.ll
===================================================================
--- llvm/test/CodeGen/X86/statepoint-vreg-details.ll
+++ llvm/test/CodeGen/X86/statepoint-vreg-details.ll
@@ -3,9 +3,9 @@
 ; the main file is easy to update with update_llc_test_checks.py
 
 ; This run is to demonstrate what MIR SSA looks like.
-; RUN: llc -max-registers-for-gc-values=4 -stop-after finalize-isel < %s | FileCheck --check-prefix=CHECK-VREG %s
+; RUN: llc -use-registers-for-dead-gc-deopt-values=false -max-registers-for-gc-values=4 -stop-after finalize-isel < %s | FileCheck --check-prefix=CHECK-VREG %s
 ; This run is to demonstrate register allocator work.
-; RUN: llc -max-registers-for-gc-values=4 -stop-after virtregrewriter < %s | FileCheck --check-prefix=CHECK-PREG %s
+; RUN: llc -use-registers-for-dead-gc-deopt-values=false -max-registers-for-gc-values=4 -stop-after virtregrewriter < %s | FileCheck --check-prefix=CHECK-PREG %s
 
 target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-pc-linux-gnu"
Index: llvm/test/CodeGen/X86/statepoint-vreg-dead-gc-deopt.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/X86/statepoint-vreg-dead-gc-deopt.ll
@@ -0,0 +1,40 @@
+; This file contains some of the same basic tests as statepoint-vreg.ll, but
+; focuses on examining the intermediate representation.  It's separate so that
+; the main file is easy to update with update_llc_test_checks.py
+
+; This run is to demonstrate what MIR SSA looks like.
+; RUN: llc -use-registers-for-dead-gc-deopt-values=true -max-registers-for-gc-values=4 -stop-after finalize-isel < %s | FileCheck --check-prefix=CHECK-VREG %s
+; This run is to demonstrate register allocator work.
+; RUN: llc -use-registers-for-dead-gc-deopt-values=true -max-registers-for-gc-values=4 -stop-after virtregrewriter < %s | FileCheck --check-prefix=CHECK-PREG %s
+
+target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-linux-gnu"
+
+declare dso_local void @func()
+declare dso_local void @consume(i32 addrspace(1)*)
+
+; deopt GC pointer not present in GC args can use register.
+define void @test_deopt_gcpointer(i32 addrspace(1)* %a, i32 addrspace(1)* %b) gc "statepoint-example" {
+; CHECK-VREG-LABEL: name:            test_deopt_gcpointer
+; CHECK-VREG:    %1:gr64 = COPY $rsi
+; CHECK-VREG:    %0:gr64 = COPY $rdi
+; CHECK-VREG:    %2:gr64 = STATEPOINT 0, 0, 0, @func, 2, 0, 2, 0, 2, 1, %0, 2, 1, %1(tied-def 0), 2, 0, 2, 1, 0, 0, csr_64, implicit-def $rsp, implicit-def $ssp
+; CHECK-VREG:    $rdi = COPY %2
+; CHECK-VREG:    CALL64pcrel32 @consume, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp
+; CHECK-VREG:    RET 0
+
+; CHECK-PREG-LABEL: name:            test_deopt_gcpointer
+; CHECK-PREG:    renamable $rbx = COPY $rsi
+; CHECK-PREG:    renamable $rbx = STATEPOINT 0, 0, 0, @func, 2, 0, 2, 0, 2, 1, killed renamable $rdi, 2, 1, killed renamable $rbx(tied-def 0), 2, 0, 2, 1, 0, 0, csr_64, implicit-def $rsp, implicit-def $ssp
+; CHECK-PREG:    $rdi = COPY killed renamable $rbx
+; CHECK-PREG:    CALL64pcrel32 @consume, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit-def $rsp, implicit-def $ssp
+
+  %safepoint_token = tail call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0) ["deopt" (i32 addrspace(1)* %a), "gc-live" (i32 addrspace(1)* %b)]
+  %rel = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token %safepoint_token,  i32 0, i32 0)
+  call void @consume(i32 addrspace(1)* %rel)
+  ret void
+}
+
+declare token @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
+declare dso_local i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token, i32, i32)
+
Index: llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
+++ llvm/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
@@ -64,6 +64,10 @@
     "use-registers-for-deopt-values", cl::Hidden, cl::init(false),
     cl::desc("Allow using registers for non pointer deopt args"));
 
+cl::opt<bool> UseRegistersForDeadGCDeoptValues(
+    "use-registers-for-dead-gc-deopt-values", cl::Hidden, cl::init(true),
+    cl::desc("Use registers for pointer deopt args missing in gc section"));
+
 cl::opt<bool> UseRegistersForGCPointersInLandingPad(
     "use-registers-for-gc-values-in-landing-pad", cl::Hidden, cl::init(false),
     cl::desc("Allow using registers for gc pointer in landing pad"));
@@ -618,8 +622,13 @@
   };
 
   auto requireSpillSlot = [&](const Value *V) {
-    if (isGCValue(V))
-      return !LowerAsVReg.count(Builder.getValue(V));
+    if (isGCValue(V)) {
+      SDValue SDV = Builder.getValue(V);
+      if (LoweredGCPtrs.count(SDV))
+        return false;
+      return !UseRegistersForDeadGCDeoptValues || !MaxVRegPtrs ||
+             !canPassGCPtrOnVReg(SDV);
+    }
     return !(LiveInDeopt || UseRegistersForDeoptValues);
   };
 


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