[PATCH] D85448: [PowerPC][PCRelative] Set TLS unsupported with PC relative memops

[Kamau Bridgeman via Phabricator via llvm-commits]

kamaub created this revision.
kamaub added reviewers: PowerPC, stefanp, nemanjai, NeHuang.
Herald added subscribers: llvm-commits, shchenz, kbarton, hiraditya.
Herald added a project: LLVM.
kamaub requested review of this revision.
Herald added a subscriber: wuzish.

Instroduce a fatal error if any thread local storage code is compiled
using pc relative memory operations as well as a hidden override
option `-enable-ppc-pcrel-tls` so that this support can be incrementally
added if possible.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85448

Files:
  llvm/lib/Target/PowerPC/PPCISelLowering.cpp
  llvm/test/CodeGen/PowerPC/pcrel-tls.ll


Index: llvm/test/CodeGen/PowerPC/pcrel-tls.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/PowerPC/pcrel-tls.ll
@@ -0,0 +1,20 @@
+; RUN: not --crash llc -mcpu=pwr10 -mtriple=powerpc64le-unknown-linux-gnu \
+; RUN:   -verify-machineinstrs -mattr=+pcrelative-memops -o - < %s 2>&1 | \
+; RUN:   FileCheck %s --check-prefix=CHECK-PCREL
+; RUN: not --crash llc -mcpu=pwr10 -mtriple=powerpc64le-unknown-linux-gnu \
+; RUN:   -verify-machineinstrs -mattr=+pcrelative-memops -enable-ppc-pcrel-tls \
+; RUN:   -o - < %s 2>&1 | FileCheck %s --check-prefix=CHECK-PCREL-TLS
+; RUN: llc -mcpu=pwr10 -mtriple=powerpc64le-unknown-linux-gnu \
+; RUN:   -verify-machineinstrs -mattr=-pcrelative-memops -o - < %s 2>&1 | \
+; RUN:   FileCheck %s --check-prefix=CHECK-NOPCREL
+
+; CHECK-PCREL:     Thread local storage is not supported with pc-relative addressing
+; CHECK-PCREL-TLS: TOC pointer used in a function using PC-Relative addressing!
+; CHECK-NOPCREL:   blr
+
+ at x = external thread_local global i32, align 4
+
+define i32* @testTLS() {
+entry:
+  ret i32* @x
+}
Index: llvm/lib/Target/PowerPC/PPCISelLowering.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -121,6 +121,11 @@
 static cl::opt<bool> UseAbsoluteJumpTables("ppc-use-absolute-jumptables",
 cl::desc("use absolute jump tables on ppc"), cl::Hidden);
 
+static cl::opt<bool> EnablePPCPCRelTLS(
+    "enable-ppc-pcrel-tls",
+    cl::desc("enable the use of PC relative memops in TLS instructions on PPC"),
+    cl::Hidden);
+
 STATISTIC(NumTailCalls, "Number of tail calls");
 STATISTIC(NumSiblingCalls, "Number of sibling calls");
 STATISTIC(ShufflesHandledWithVPERM, "Number of shuffles lowered to a VPERM");
@@ -2901,6 +2906,10 @@
   // which is the most useful form.  Eventually support for small and
   // large models could be added if users need it, at the cost of
   // additional complexity.
+  if (Subtarget.isUsingPCRelativeCalls())
+    assert(EnablePPCPCRelTLS &&
+           "Thread local storage is not supported with pc-relative addressing "
+           "- please compile with -mno-pcrel");
   GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);
   if (DAG.getTarget().useEmulatedTLS())
     return LowerToTLSEmulatedModel(GA, DAG);


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