[llvm] bf66003 - [MC,NVPTX] Add MCAsmPrinter support for unsigned-only data directives.

[Artem Belevich via llvm-commits]

Author: Artem Belevich
Date: 2020-07-20T16:24:41-07:00
New Revision: bf66003a4f9115beb4a8a240b5327b3cc41be9cc

URL: https://github.com/llvm/llvm-project/commit/bf66003a4f9115beb4a8a240b5327b3cc41be9cc
DIFF: https://github.com/llvm/llvm-project/commit/bf66003a4f9115beb4a8a240b5327b3cc41be9cc.diff

LOG: [MC,NVPTX] Add MCAsmPrinter support for unsigned-only data directives.

PTX does not support negative values in .bNN data directives and we must
typecast such values to unsigned before printing them.

MCAsmInfo can now specify whether such casting is necessary for particular
target.

Differential Revision: https://reviews.llvm.org/D83423

Added: 
    

Modified: 
    llvm/include/llvm/MC/MCAsmInfo.h
    llvm/lib/MC/MCExpr.cpp
    llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
    llvm/test/DebugInfo/NVPTX/packed_bitfields.ll

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/MC/MCAsmInfo.h b/llvm/include/llvm/MC/MCAsmInfo.h
index 46c5a111c891..0f9d503045d8 100644
--- a/llvm/include/llvm/MC/MCAsmInfo.h
+++ b/llvm/include/llvm/MC/MCAsmInfo.h
@@ -209,6 +209,9 @@ class MCAsmInfo {
   const char *Data32bitsDirective;
   const char *Data64bitsDirective;
 
+  /// True if data directives support signed values
+  bool SupportsSignedData = true;
+
   /// If non-null, a directive that is used to emit a word which should be
   /// relocated as a 64-bit GP-relative offset, e.g. .gpdword on Mips.  Defaults
   /// to nullptr.
@@ -436,6 +439,7 @@ class MCAsmInfo {
   const char *getData16bitsDirective() const { return Data16bitsDirective; }
   const char *getData32bitsDirective() const { return Data32bitsDirective; }
   const char *getData64bitsDirective() const { return Data64bitsDirective; }
+  bool supportsSignedData() const { return SupportsSignedData; }
   const char *getGPRel64Directive() const { return GPRel64Directive; }
   const char *getGPRel32Directive() const { return GPRel32Directive; }
   const char *getDTPRel64Directive() const { return DTPRel64Directive; }

diff  --git a/llvm/lib/MC/MCExpr.cpp b/llvm/lib/MC/MCExpr.cpp
index ecf63b10f73f..9b78eca35caa 100644
--- a/llvm/lib/MC/MCExpr.cpp
+++ b/llvm/lib/MC/MCExpr.cpp
@@ -47,6 +47,8 @@ void MCExpr::print(raw_ostream &OS, const MCAsmInfo *MAI, bool InParens) const {
     auto Value = cast<MCConstantExpr>(*this).getValue();
     auto PrintInHex = cast<MCConstantExpr>(*this).useHexFormat();
     auto SizeInBytes = cast<MCConstantExpr>(*this).getSizeInBytes();
+    if (Value < 0 && MAI && !MAI->supportsSignedData())
+      PrintInHex = true;
     if (PrintInHex)
       switch (SizeInBytes) {
       default:

diff  --git a/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp b/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
index aef0eed6ab9a..f275011018a3 100644
--- a/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
+++ b/llvm/lib/Target/NVPTX/MCTargetDesc/NVPTXMCAsmInfo.cpp
@@ -47,6 +47,7 @@ NVPTXMCAsmInfo::NVPTXMCAsmInfo(const Triple &TheTriple,
   AscizDirective = nullptr; // not supported
   SupportsQuotedNames = false;
   SupportsExtendedDwarfLocDirective = false;
+  SupportsSignedData = false;
 
   // @TODO: Can we just disable this?
   WeakDirective = "\t// .weak\t";

diff  --git a/llvm/test/DebugInfo/NVPTX/packed_bitfields.ll b/llvm/test/DebugInfo/NVPTX/packed_bitfields.ll
index 36433064fa92..63516f597272 100644
--- a/llvm/test/DebugInfo/NVPTX/packed_bitfields.ll
+++ b/llvm/test/DebugInfo/NVPTX/packed_bitfields.ll
@@ -14,7 +14,8 @@
 ; CHECK:      .b8 3    // DW_AT_decl_line
 ; CHECK-NEXT: .b8 1    // DW_AT_byte_size
 ; CHECK-NEXT: .b8 6    // DW_AT_bit_size
-; CHECK-NEXT: .b64 -1  // DW_AT_bit_offset
+; Negative offset must be encoded as an unsigned integer.
+; CHECK-NEXT: .b64 0xffffffffffffffff // DW_AT_bit_offset
 ; CHECK-NEXT: .b8 2    // DW_AT_data_member_location
 
 %struct.anon = type { i16 }