[PATCH] D116735: [RISCV] Adjust RISCV data layout by using n32:64 in layout string

[Jun Sha via Phabricator via llvm-commits]

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Although i32 type is illegal in llvm back-end, I don't think it necessory to keep consistent for layout string.
In the current version, layout string is "e-m:e-p:64:64-i64:64-i128:128-n64-S128" for 64-bit arch where native integer type is only i64. However, under this circumstance, some middle-end passes like LSRs may be influenced due to the predictor("DL.isLegalInteger") result.

Let's look at line 157-162 in IVUsers.cpp.

- // LSR is not APInt clean, do not touch integers bigger than 64-bits. // Also avoid creating IVs of non-native types. For example, we don't want a // 64-bit IV in 32-bit code just because the loop has one 64-bit cast. uint64_t Width = SE->getTypeSizeInBits(I->getType()); if (Width > 64 || !DL.isLegalInteger(Width)) return false;**

Now I try to use n32:64 in layout string without degression of some other passes that use this info.


https://reviews.llvm.org/D116735

Files:
  clang/lib/Basic/Targets/RISCV.h
  llvm/lib/Target/RISCV/RISCVTargetMachine.cpp


Index: llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
===================================================================
--- llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
+++ llvm/lib/Target/RISCV/RISCVTargetMachine.cpp
@@ -46,7 +46,7 @@
 
 static StringRef computeDataLayout(const Triple &TT) {
   if (TT.isArch64Bit())
-    return "e-m:e-p:64:64-i64:64-i128:128-n64-S128";
+    return "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128";
   assert(TT.isArch32Bit() && "only RV32 and RV64 are currently supported");
   return "e-m:e-p:32:32-i64:64-n32-S128";
 }
Index: clang/lib/Basic/Targets/RISCV.h
===================================================================
--- clang/lib/Basic/Targets/RISCV.h
+++ clang/lib/Basic/Targets/RISCV.h
@@ -133,7 +133,7 @@
       : RISCVTargetInfo(Triple, Opts) {
     LongWidth = LongAlign = PointerWidth = PointerAlign = 64;
     IntMaxType = Int64Type = SignedLong;
-    resetDataLayout("e-m:e-p:64:64-i64:64-i128:128-n64-S128");
+    resetDataLayout("e-m:e-p:64:64-i64:64-i128:128-n32:64-S128");
   }
 
   bool setABI(const std::string &Name) override {


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