[llvm] r370600 - [X86] Compress the flag bits in the folding tables to make room for more bits in an upcoming patch.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Sat Aug 31 16:52:21 2019
New Revision: 370600

URL: http://llvm.org/viewvc/llvm-project?rev=370600&view=rev
Log:
[X86] Compress the flag bits in the folding tables to make room for more bits in an upcoming patch.

Modified:
    llvm/trunk/lib/Target/X86/X86InstrFoldTables.h
    llvm/trunk/lib/Target/X86/X86InstrInfo.cpp

Modified: llvm/trunk/lib/Target/X86/X86InstrFoldTables.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrFoldTables.h?rev=370600&r1=370599&r2=370600&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrFoldTables.h (original)
+++ llvm/trunk/lib/Target/X86/X86InstrFoldTables.h Sat Aug 31 16:52:21 2019
@@ -19,35 +19,39 @@ namespace llvm {
 
 enum {
   // Select which memory operand is being unfolded.
-  // (stored in bits 0 - 3)
+  // (stored in bits 0 - 2)
   TB_INDEX_0    = 0,
   TB_INDEX_1    = 1,
   TB_INDEX_2    = 2,
   TB_INDEX_3    = 3,
   TB_INDEX_4    = 4,
-  TB_INDEX_MASK = 0xf,
+  TB_INDEX_MASK = 0x7,
 
   // Do not insert the reverse map (MemOp -> RegOp) into the table.
   // This may be needed because there is a many -> one mapping.
-  TB_NO_REVERSE   = 1 << 4,
+  TB_NO_REVERSE   = 1 << 3,
 
   // Do not insert the forward map (RegOp -> MemOp) into the table.
   // This is needed for Native Client, which prohibits branch
   // instructions from using a memory operand.
-  TB_NO_FORWARD   = 1 << 5,
+  TB_NO_FORWARD   = 1 << 4,
 
-  TB_FOLDED_LOAD  = 1 << 6,
-  TB_FOLDED_STORE = 1 << 7,
+  TB_FOLDED_LOAD  = 1 << 5,
+  TB_FOLDED_STORE = 1 << 6,
+  // Unused bit 7
 
   // Minimum alignment required for load/store.
-  // Used for RegOp->MemOp conversion.
-  // (stored in bits 8 - 15)
+  // Used for RegOp->MemOp conversion. Encoded as Log2(Align) + 1 to allow 0
+  // to mean align of 0.
+  // (stored in bits 8 - 11)
   TB_ALIGN_SHIFT = 8,
-  TB_ALIGN_NONE  =    0 << TB_ALIGN_SHIFT,
-  TB_ALIGN_16    =   16 << TB_ALIGN_SHIFT,
-  TB_ALIGN_32    =   32 << TB_ALIGN_SHIFT,
-  TB_ALIGN_64    =   64 << TB_ALIGN_SHIFT,
-  TB_ALIGN_MASK  = 0xff << TB_ALIGN_SHIFT
+  TB_ALIGN_NONE  =   0 << TB_ALIGN_SHIFT,
+  TB_ALIGN_16    =   5 << TB_ALIGN_SHIFT,
+  TB_ALIGN_32    =   6 << TB_ALIGN_SHIFT,
+  TB_ALIGN_64    =   7 << TB_ALIGN_SHIFT,
+  TB_ALIGN_MASK  = 0xf << TB_ALIGN_SHIFT,
+
+  // Unused bits 12-15
 };
 
 // This struct is used for both the folding and unfold tables. They KeyOp

Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.cpp?rev=370600&r1=370599&r2=370600&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86InstrInfo.cpp Sat Aug 31 16:52:21 2019
@@ -4805,6 +4805,7 @@ MachineInstr *X86InstrInfo::foldMemoryOp
   if (I != nullptr) {
     unsigned Opcode = I->DstOp;
     unsigned MinAlign = (I->Flags & TB_ALIGN_MASK) >> TB_ALIGN_SHIFT;
+    MinAlign = MinAlign ? 1 << (MinAlign - 1) : 0;
     if (Align < MinAlign)
       return nullptr;
     bool NarrowToMOV32rm = false;