[AIX][XCOFF] add symbol priority for the llvm-objdump -D -symbol-description

SUMMARY:
when there are two symbol has the same address. llvm-objdump -D -symbol-description will select symbol based on the following rule:

1. using Label first if there is a Label symbol.
2. If there is not Label, using a symbol which has Storage Mapping class.
3. if more than one symbol has storage mapping class, put the TC0 has the low priority, for other storage mapping class , compare based on the value.

Reviewers: James Henderson ,hubert.reinterpretcast,

Differential Revision: https://reviews.llvm.org/D78387

1 files changed, 53 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp b/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp
index 373916f..40ffd1f 100644
--- a/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp
+++ b/llvm/lib/MC/MCDisassembler/MCDisassembler.cpp
@@ -43,3 +43,56 @@ void MCDisassembler::tryAddingPcLoadReferenceComment(int64_t Value,
 void MCDisassembler::setSymbolizer(std::unique_ptr<MCSymbolizer> Symzer) {
   Symbolizer = std::move(Symzer);
 }
+
+#define SMC_PCASE(A, P)                                                         \
+  case XCOFF::XMC_##A:                                                         \
+    return P;
+
+uint8_t getSMCPriority(XCOFF::StorageMappingClass SMC) {
+  switch (SMC) {
+    SMC_PCASE(PR, 1)
+    SMC_PCASE(RO, 1)
+    SMC_PCASE(DB, 1)
+    SMC_PCASE(GL, 1)
+    SMC_PCASE(XO, 1)
+    SMC_PCASE(SV, 1)
+    SMC_PCASE(SV64, 1)
+    SMC_PCASE(SV3264, 1)
+    SMC_PCASE(TI, 1)
+    SMC_PCASE(TB, 1)
+    SMC_PCASE(RW, 1)
+    SMC_PCASE(TC0, 0)
+    SMC_PCASE(TC, 1)
+    SMC_PCASE(TD, 1)
+    SMC_PCASE(DS, 1)
+    SMC_PCASE(UA, 1)
+    SMC_PCASE(BS, 1)
+    SMC_PCASE(UC, 1)
+    SMC_PCASE(TL, 1)
+    SMC_PCASE(UL, 1)
+    SMC_PCASE(TE, 1)
+#undef SMC_PCASE
+  }
+  return 0;
+}
+
+/// The function is for symbol sorting when symbols have the same address.
+/// The symbols in the same section are sorted in ascending order.
+/// llvm-objdump -D will choose the highest priority symbol to display when
+/// there are symbols with the same address.
+bool XCOFFSymbolInfo::operator<(const XCOFFSymbolInfo &SymInfo) const {
+  // Label symbols have higher priority than non-label symbols.
+  if (IsLabel != SymInfo.IsLabel)
+    return SymInfo.IsLabel;
+
+  // Symbols with a StorageMappingClass have higher priority than those without.
+  if (StorageMappingClass.hasValue() != SymInfo.StorageMappingClass.hasValue())
+    return SymInfo.StorageMappingClass.hasValue();
+
+  if (StorageMappingClass.hasValue()) {
+    return getSMCPriority(StorageMappingClass.getValue()) <
+           getSMCPriority(SymInfo.StorageMappingClass.getValue());
+  }
+
+  return false;
+}