[PATCH] D104473: RISCV: clean up target expression handling

[Saleem Abdulrasool via Phabricator via llvm-commits]

compnerd updated this revision to Diff 352787.
compnerd added a comment.

Address feedback from @MaskRay


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104473/new/

https://reviews.llvm.org/D104473

Files:
  llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
  llvm/test/MC/RISCV/expressions.s


Index: llvm/test/MC/RISCV/expressions.s
===================================================================
--- /dev/null
+++ llvm/test/MC/RISCV/expressions.s
@@ -0,0 +1,29 @@
+# RUN: not llvm-mc -triple riscv32 -filetype obj %s -o /dev/null 2>&1 | FileCheck %s
+
+.Ltmp1:
+	.quad	tls
+
+	lui a0, %hi(tls+0-.Ltmp1)
+# CHECK: :6:2: error: expected relocatable expression
+	lw a0, %lo(tls+0-.Ltmp1)(t0)
+# CHECK: :8:2: error: expected relocatable expression
+	lui a0, %tprel_hi(tls+0-.Ltmp1)
+# CHECK: :10:2: error: expected relocatable expression
+	add a0, a0, tp, %tprel_add(tls+0-.Ltmp1)
+# CHECK: :12:2: error: expected relocatable expression
+	addi a0, a0, %tprel_lo(tls+0-.Ltmp1)
+# CHECK: :14:2: error: expected relocatable expression
+	auipc a0, %tls_ie_pcrel_hi(tls+0-.Ltmp1)
+# CHECK: :16:2: error: expected relocatable expression
+	auipc a0, %tls_gd_pcrel_hi(tls+0-.Ltmp1)
+# CHECK: :18:2: error: expected relocatable expression
+	auipc a0, %pcrel_hi(tls-.Ltmp1)
+# CHECK: :20:2: error: expected relocatable expression
+	auipc a0, %got_pcrel_hi(tls-.Ltmp1)
+# CHECK: :22:2: error: expected relocatable expression
+	addi a0, a0, %pcrel_lo(tls-.Ltmp1)
+# CHECK: :24:2: error: expected relocatable expression
+
+#	tail tls+32
+#	tail tls-tls
+# _ :28:2: error: expected relocatable expression
Index: llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
===================================================================
--- llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
+++ llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCExpr.cpp
@@ -92,33 +92,16 @@
 bool RISCVMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
                                             const MCAsmLayout *Layout,
                                             const MCFixup *Fixup) const {
-  bool IsSymbolicDifference = false;
-  if (const auto *MBE = dyn_cast<MCBinaryExpr>(getSubExpr())) {
-    if (isa<MCBinaryExpr>(MBE->getLHS()) && isa<MCConstantExpr>(MBE->getRHS()))
-      MBE = cast<MCBinaryExpr>(MBE->getLHS());
-    IsSymbolicDifference = isa<MCSymbolRefExpr>(MBE->getLHS()) &&
-                           isa<MCSymbolRefExpr>(MBE->getRHS());
-  }
+  // Explicitly drop the layout and assembler to prevent any symbolic folding in
+  // the expression handling.  This is required to preserve symbolic difference
+  // expressions to emit the paired relocations.
+  if (!getSubExpr()->evaluateAsRelocatable(Res, nullptr, nullptr))
+    return false;
 
-  // Some custom fixup types are not valid with symbol difference expressions
-  if (IsSymbolicDifference) {
-    switch (getKind()) {
-    default:
-      break;
-    case VK_RISCV_LO:
-    case VK_RISCV_HI:
-    case VK_RISCV_PCREL_LO:
-    case VK_RISCV_PCREL_HI:
-    case VK_RISCV_GOT_HI:
-    case VK_RISCV_TPREL_LO:
-    case VK_RISCV_TPREL_HI:
-    case VK_RISCV_TPREL_ADD:
-    case VK_RISCV_TLS_GOT_HI:
-    case VK_RISCV_TLS_GD_HI:
-      return false;
-    }
-  }
-  return getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup);
+  Res =
+      MCValue::get(Res.getSymA(), Res.getSymB(), Res.getConstant(), getKind());
+  // Custom fixup types are not valid with symbol difference expressions.
+  return Res.getSymB() ? getKind() == VK_RISCV_None : true;
 }
 
 void RISCVMCExpr::visitUsedExpr(MCStreamer &Streamer) const {


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