[PATCH] D61584: [DebugInfo] Some fields do not need relocations even relax is enabled.

[Hsiangkai Wang via Phabricator via llvm-commits]

HsiangKai updated this revision to Diff 206120.
HsiangKai added a comment.

Fix bugs.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D61584/new/

https://reviews.llvm.org/D61584

Files:
  lib/MC/MCExpr.cpp
  test/DebugInfo/RISCV/relax-debug-frame.ll


Index: test/DebugInfo/RISCV/relax-debug-frame.ll
===================================================================
--- test/DebugInfo/RISCV/relax-debug-frame.ll
+++ test/DebugInfo/RISCV/relax-debug-frame.ll
@@ -2,10 +2,12 @@
 ; RUN:     | llvm-readobj -r | FileCheck -check-prefix=RELAX %s
 ;
 ; RELAX: .rela.{{eh|debug}}_frame {
-; RELAX: R_RISCV_ADD32
-; RELAX: R_RISCV_SUB32
-; RELAX: R_RISCV_SET6
-; RELAX: R_RISCV_SUB6
+; RELAX-NOT: 0x0 R_RISCV_ADD32
+; RELAX-NOT: 0x0 R_RISCV_SUB32
+; RELAX: 0x20 R_RISCV_ADD32
+; RELAX: 0x20 R_RISCV_SUB32
+; RELAX: 0x25 R_RISCV_SET6
+; RELAX: 0x25 R_RISCV_SUB6
 source_filename = "frame.c"
 
 ; Function Attrs: noinline nounwind optnone
Index: lib/MC/MCExpr.cpp
===================================================================
--- lib/MC/MCExpr.cpp
+++ lib/MC/MCExpr.cpp
@@ -566,6 +566,24 @@
   A = B = nullptr;
 }
 
+static bool canFold(const MCAssembler *Asm, const MCSymbolRefExpr *A,
+                    const MCSymbolRefExpr *B, bool InSet) {
+  if (InSet)
+    return true;
+
+  if (!Asm->getBackend().requiresDiffExpressionRelocations())
+    return true;
+
+  const MCSymbol &CheckSym = A ? A->getSymbol() : B->getSymbol();
+  if (!CheckSym.isInSection())
+    return true;
+
+  if (!CheckSym.getSection().hasInstructions())
+    return true;
+
+  return false;
+}
+
 /// Evaluate the result of an add between (conceptually) two MCValues.
 ///
 /// This routine conceptually attempts to construct an MCValue:
@@ -606,8 +624,7 @@
   // the backend requires this to be emitted as individual relocations, unless
   // the InSet flag is set to get the current difference anyway (used for
   // example to calculate symbol sizes).
-  if (Asm &&
-      (InSet || !Asm->getBackend().requiresDiffExpressionRelocations())) {
+  if (Asm && canFold(Asm, LHS_A, LHS_B, InSet)) {
     // First, fold out any differences which are fully resolved. By
     // reassociating terms in
     //   Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).


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