opt: Try to respect target-abi command line option (#169604)

Mips seems kind of broken with these options. n32 seems to
override the 64-bit arch with 32-bit pointers, and trying
to use any 32-bit mips triple also just errors with any
options.

Author: arsenm

llvm/include/llvm/MC/MCTargetOptionsCommandFlags.h

@@ -22,6 +22,7 @@ namespace llvm {
 
 class MCTargetOptions;
 enum class EmitDwarfUnwindType;
+class StringRef;
 
 namespace mc {
 
@@ -62,9 +63,9 @@ LLVM_ABI bool getX86RelaxRelocations();
 
 LLVM_ABI bool getX86Sse2Avx();
 
-LLVM_ABI std::string getABIName();
+LLVM_ABI StringRef getABIName();
 
-LLVM_ABI std::string getAsSecureLogFile();
+LLVM_ABI StringRef getAsSecureLogFile();
 
 /// Create this object with static storage to register mc-related command
 /// line options.

llvm/lib/MC/MCTargetOptionsCommandFlags.cpp

@@ -24,6 +24,13 @@ using namespace llvm;
     return *NAME##View;                                                        \
   }
 
+#define MCSTROPT(NAME)                                                         \
+  static cl::opt<std::string> *NAME##View;                                     \
+  StringRef llvm::mc::get##NAME() {                                            \
+    assert(NAME##View && "RegisterMCTargetOptionsFlags not created.");         \
+    return *NAME##View;                                                        \
+  }
+
 #define MCOPT_EXP(TY, NAME)                                                    \
   MCOPT(TY, NAME)                                                              \
   std::optional<TY> llvm::mc::getExplicit##NAME() {                            \
@@ -52,8 +59,8 @@ MCOPT(bool, Crel)
 MCOPT(bool, ImplicitMapSyms)
 MCOPT(bool, X86RelaxRelocations)
 MCOPT(bool, X86Sse2Avx)
-MCOPT(std::string, ABIName)
-MCOPT(std::string, AsSecureLogFile)
+MCSTROPT(ABIName)
+MCSTROPT(AsSecureLogFile)
 
 llvm::mc::RegisterMCTargetOptionsFlags::RegisterMCTargetOptionsFlags() {
 #define MCBINDOPT(NAME)                                                        \

llvm/test/tools/opt/infer-data-layout-target-abi.ll

@@ -0,0 +1,9 @@
+; REQUIRES: mips-registered-target
+;; Check that we infer the correct datalayout from a target triple
+; RUN: opt -mtriple=mips64-- -S -passes=no-op-module -target-abi=n32 < %s | FileCheck -check-prefix=N32 %s
+; RUN: opt -mtriple=mips64-- -S -passes=no-op-module -target-abi=n64 < %s | FileCheck -check-prefix=N64 %s
+
+target datalayout = ""
+
+; N32: target datalayout = "E-m:e-p:32:32-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+; N64: target datalayout = "E-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"

llvm/tools/opt/optdriver.cpp

@@ -37,6 +37,7 @@
 #include "llvm/InitializePasses.h"
 #include "llvm/LinkAllIR.h"
 #include "llvm/LinkAllPasses.h"
+#include "llvm/MC/MCTargetOptionsCommandFlags.h"
 #include "llvm/MC/TargetRegistry.h"
 #include "llvm/Passes/PassPlugin.h"
 #include "llvm/Remarks/HotnessThresholdParser.h"
@@ -516,6 +517,8 @@ optMain(int argc, char **argv,
 
   codegen::MaybeEnableStatistics();
 
+  StringRef ABIName = mc::getABIName(); // FIXME: Handle module flag.
+
   // Load the input module...
   auto SetDataLayout = [&](StringRef IRTriple,
                            StringRef IRLayout) -> std::optional<std::string> {
@@ -541,7 +544,7 @@ optMain(int argc, char **argv,
 
     Triple TT(TripleStr);
 
-    std::string Str = TT.computeDataLayout();
+    std::string Str = TT.computeDataLayout(ABIName);
     if (Str.empty()) {
       errs() << argv[0]
              << ": warning: failed to infer data layout from target triple\n";
@@ -677,9 +680,7 @@ optMain(int argc, char **argv,
 
   RTLIB::RuntimeLibcallsInfo RTLCI(ModuleTriple, codegen::getExceptionModel(),
                                    codegen::getFloatABIForCalls(),
-                                   codegen::getEABIVersion(),
-                                   "", // FIXME: Get ABI name from MCOptions
-                                   VecLib);
+                                   codegen::getEABIVersion(), ABIName, VecLib);
 
   // The -disable-simplify-libcalls flag actually disables all builtin optzns.
   if (DisableSimplifyLibCalls)