[llvm] r237597 - [PlaceSafepoints] Assertion on that gc_result can not have preceding phis should only apply to invoke statepoint

[Chen Li]

Author: chenli
Date: Mon May 18 14:02:25 2015
New Revision: 237597

URL: http://llvm.org/viewvc/llvm-project?rev=237597&view=rev
Log:
[PlaceSafepoints] Assertion on that gc_result can not have preceding phis should only apply to invoke statepoint

Summary: When PlaceSafepoints pass replaces old return result with gc_result from statepoint, it asserts that gc_result can not have preceding phis in its parent block. This is only true on invoke statepoint, which terminates the block and puts its result at the beginning of the normal successor block. Call statepoint does not terminate the block and thus its result is in the same block with it. There should be no restriction on whether there are phis or not.

Reviewers: reames, igor-laevsky

Reviewed By: igor-laevsky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9803

Added:
    llvm/trunk/test/Transforms/PlaceSafepoints/call_gc_result.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp?rev=237597&r1=237596&r2=237597&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp Mon May 18 14:02:25 2015
@@ -716,8 +716,8 @@ bool PlaceSafepoints::runOnFunction(Func
     CallSite &CS = ParsePointNeeded[i];
     Value *GCResult = Results[i];
     if (GCResult) {
-      // Can not RAUW for the gc result in case of phi nodes preset.
-      assert(!isa<PHINode>(cast<Instruction>(GCResult)->getParent()->begin()));
+      // Can not RAUW for the invoke gc result in case of phi nodes preset.
+      assert(CS.isCall() || !isa<PHINode>(cast<Instruction>(GCResult)->getParent()->begin()));
 
       // Replace all uses with the new call
       CS.getInstruction()->replaceAllUsesWith(GCResult);

Added: llvm/trunk/test/Transforms/PlaceSafepoints/call_gc_result.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PlaceSafepoints/call_gc_result.ll?rev=237597&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/PlaceSafepoints/call_gc_result.ll (added)
+++ llvm/trunk/test/Transforms/PlaceSafepoints/call_gc_result.ll Mon May 18 14:02:25 2015
@@ -0,0 +1,38 @@
+;; RUN: opt %s -place-safepoints -S | FileCheck %s
+
+;; This test is to verify that gc_result from a call statepoint
+;; can have preceding phis in its parent basic block. Unlike
+;; invoke statepoint, call statepoint does not terminate the
+;; block, and thus its gc_result is in the same block with the
+;; call statepoint.
+
+declare i32 @foo()
+
+define i32 @test1(i1 %cond, i32 %a) gc "statepoint-example" {
+entry:
+  br i1 %cond, label %branch1, label %branch2
+  
+branch1:
+  %b = add i32 %a, 1
+  br label %merge
+ 
+branch2:
+  br label %merge
+
+merge:
+;; CHECK: 		%phi = phi i32 [ %a, %branch2 ], [ %b, %branch1 ]
+;; CHECK-NEXT:  %safepoint_token.1 = call i32 (i64, i32, i32 ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i32f(i64 2882400000, i32 0, i32 ()* @foo, i32 0, i32 0, i32 0, i32 0)
+;; CHECK-NEXT:  %ret.2 = call i32 @llvm.experimental.gc.result.i32(i32 %safepoint_token.1)
+  %phi = phi i32 [ %a, %branch2 ], [ %b, %branch1 ]
+  %ret = call i32 @foo()
+  ret i32 %ret
+}
+
+; This function is inlined when inserting a poll.
+declare void @do_safepoint()
+define void @gc.safepoint_poll() {
+; CHECK-LABEL: gc.safepoint_poll
+entry:
+  call void @do_safepoint()
+  ret void
+}