[PATCH] D33573: [PPC] Fix atomics lowering in DAG lowering.

[Tim Shen via Phabricator via llvm-commits]

timshen created this revision.
Herald added a subscriber: nemanjai.

I forgot to forward the chain, causing some missing instruction
dependencies. The test crashes the compiler without this patch.

Inspired by the test case, https://reviews.llvm.org/D33519 also tries to remove the extra sync.


https://reviews.llvm.org/D33573

Files:
  llvm/lib/Target/PowerPC/PPCISelLowering.cpp
  llvm/test/CodeGen/PowerPC/atomics-constant.ll


Index: llvm/test/CodeGen/PowerPC/atomics-constant.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/atomics-constant.ll
@@ -0,0 +1,23 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s | FileCheck %s
+
+target triple = "powerpc64le-unknown-linux-gnu"
+
+ at a = constant i64 zeroinitializer
+
+define i64 @foo() {
+; CHECK-LABEL: foo:
+; CHECK:       # BB#0: # %entry
+; CHECK-NEXT:    addis 3, 2, .LC0 at toc@ha
+; CHECK-NEXT:    li 4, 0
+; CHECK-NEXT:    ld 3, .LC0 at toc@l(3)
+; CHECK-NEXT:    cmpw 7, 4, 4
+; CHECK-NEXT:    ld 3, 0(3)
+; CHECK-NEXT:    bne- 7, .+4
+; CHECK-NEXT:    isync
+; CHECK-NEXT:    li 3, 0
+; CHECK-NEXT:    blr
+entry:
+  %value = load atomic i64, i64* @a acquire, align 8
+  ret i64 %value
+}
Index: llvm/lib/Target/PowerPC/PPCISelLowering.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -8296,10 +8296,12 @@
   SDLoc DL(Op);
   switch (cast<ConstantSDNode>(Op.getOperand(ArgStart))->getZExtValue()) {
   case Intrinsic::ppc_cfence: {
+    assert(ArgStart == 1);
     assert(Subtarget.isPPC64() && "Only 64-bit is supported for now.");
     return SDValue(DAG.getMachineNode(PPC::CFENCE8, DL, MVT::Other,
                                       DAG.getNode(ISD::ANY_EXTEND, DL, MVT::i64,
-                                                  Op.getOperand(ArgStart + 1))),
+                                                  Op.getOperand(ArgStart + 1)),
+                                      Op.getOperand(0)),
                    0);
   }
   default:


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