[AMDGPU] Flip the default value of maybeAtomic. NFCI. (llvm#75220)

In practice maybeAtomic = 0 is used to prevent SIMemoryLegalizer from
interfering with instructions that are mayLoad or mayStore but lack
MachineMemOperands. These instructions should be the exception not the
rule, so this patch sets maybeAtomic = 1 by default and only overrides
it to 0 where necessary.

llvm/lib/Target/AMDGPU/BUFInstructions.td

@@ -503,7 +503,6 @@ class MUBUF_Load_Pseudo <string opName,
   let has_vdata = !not(!or(isLds, isLdsOpc));
   let mayLoad = 1;
   let mayStore = isLds;
-  let maybeAtomic = 1;
   let Uses = !if(!or(isLds, isLdsOpc) , [EXEC, M0], [EXEC]);
   let tfe = isTFE;
   let lds = isLds;
@@ -610,7 +609,6 @@ class MUBUF_Store_Pseudo <string opName,
                     getAddrName<addrKindCopy>.ret;
   let mayLoad = 0;
   let mayStore = 1;
-  let maybeAtomic = 1;
   let elements = getMUBUFElements<store_vt>.ret;
   let tfe = isTFE;
 }
@@ -671,7 +669,6 @@ class MUBUF_Pseudo_Store_Lds<string opName>
   let LGKM_CNT = 1;
   let mayLoad = 1;
   let mayStore = 1;
-  let maybeAtomic = 1;
 
   let has_vdata = 0;
   let has_vaddr = 0;
@@ -735,7 +732,6 @@ class MUBUF_Atomic_Pseudo<string opName,
   let has_glc = 0;
   let has_dlc = 0;
   let has_sccb = 1;
-  let maybeAtomic = 1;
   let AsmMatchConverter = "cvtMubufAtomic";
 }
 

llvm/lib/Target/AMDGPU/DSDIRInstructions.td

@@ -73,6 +73,7 @@ class DSDIR_Common<string opName, string asm = "", dag ins, bit direct> :
   let hasSideEffects = 0;
   let mayLoad = 1;
   let mayStore = 0;
+  let maybeAtomic = 0;
 
   string Mnemonic = opName;
   let UseNamedOperandTable = 1;

llvm/lib/Target/AMDGPU/DSInstructions.td

@@ -19,7 +19,6 @@ class DS_Pseudo <string opName, dag outs, dag ins, string asmOps, list<dag> patt
   // Most instruction load and store data, so set this as the default.
   let mayLoad = 1;
   let mayStore = 1;
-  let maybeAtomic = 1;
 
   let hasSideEffects = 0;
   let SchedRW = [WriteLDS];

llvm/lib/Target/AMDGPU/EXPInstructions.td

@@ -20,6 +20,7 @@ class EXPCommon<bit row, bit done, string asm = ""> : InstSI<
   let EXP_CNT = 1;
   let mayLoad = done;
   let mayStore = 1;
+  let maybeAtomic = 0;
   let UseNamedOperandTable = 1;
   let Uses = !if(row, [EXEC, M0], [EXEC]);
   let SchedRW = [WriteExport];

llvm/lib/Target/AMDGPU/FLATInstructions.td

@@ -215,7 +215,6 @@ class FLAT_Load_Pseudo <string opName, RegisterClass regClass,
   let has_saddr = HasSaddr;
   let enabled_saddr = EnableSaddr;
   let PseudoInstr = opName#!if(!and(HasSaddr, EnableSaddr), "_SADDR", "");
-  let maybeAtomic = 1;
 
   let Constraints = !if(HasTiedOutput, "$vdst = $vdst_in", "");
   let DisableEncoding = !if(HasTiedOutput, "$vdst_in", "");
@@ -237,7 +236,6 @@ class FLAT_Store_Pseudo <string opName, RegisterClass vdataClass,
   let has_saddr = HasSaddr;
   let enabled_saddr = EnableSaddr;
   let PseudoInstr = opName#!if(!and(HasSaddr, EnableSaddr), "_SADDR", "");
-  let maybeAtomic = 1;
 }
 
 multiclass FLAT_Global_Load_Pseudo<string opName, RegisterClass regClass, bit HasTiedInput = 0> {
@@ -263,7 +261,6 @@ class FLAT_Global_Load_AddTid_Pseudo <string opName, RegisterClass regClass,
   let has_vaddr = 0;
   let has_saddr = 1;
   let enabled_saddr = EnableSaddr;
-  let maybeAtomic = 1;
   let PseudoInstr = opName#!if(EnableSaddr, "_SADDR", "");
 
   let Constraints = !if(HasTiedOutput, "$vdst = $vdst_in", "");
@@ -330,7 +327,6 @@ class FLAT_Global_Store_AddTid_Pseudo <string opName, RegisterClass vdataClass,
   let has_vaddr = 0;
   let has_saddr = 1;
   let enabled_saddr = EnableSaddr;
-  let maybeAtomic = 1;
   let PseudoInstr = opName#!if(EnableSaddr, "_SADDR", "");
 }
 
@@ -401,7 +397,6 @@ class FLAT_Scratch_Load_Pseudo <string opName, RegisterClass regClass,
   let has_sve = EnableSVE;
   let sve = EnableVaddr;
   let PseudoInstr = opName#!if(EnableSVE, "_SVS", !if(EnableSaddr, "_SADDR", !if(EnableVaddr, "", "_ST")));
-  let maybeAtomic = 1;
 
   let Constraints = !if(HasTiedOutput, "$vdst = $vdst_in", "");
   let DisableEncoding = !if(HasTiedOutput, "$vdst_in", "");
@@ -430,7 +425,6 @@ class FLAT_Scratch_Store_Pseudo <string opName, RegisterClass vdataClass, bit En
   let has_sve = EnableSVE;
   let sve = EnableVaddr;
   let PseudoInstr = opName#!if(EnableSVE, "_SVS", !if(EnableSaddr, "_SADDR", !if(EnableVaddr, "", "_ST")));
-  let maybeAtomic = 1;
 }
 
 multiclass FLAT_Scratch_Load_Pseudo<string opName, RegisterClass regClass, bit HasTiedOutput = 0> {
@@ -520,7 +514,6 @@ class FLAT_AtomicNoRet_Pseudo<string opName, dag outs, dag ins,
     let has_vdst = 0;
     let has_sccb  = 1;
     let sccbValue = 0;
-    let maybeAtomic = 1;
     let IsAtomicNoRet = 1;
 }
 

llvm/lib/Target/AMDGPU/SIInstrFormats.td

@@ -91,7 +91,7 @@ class InstSI <dag outs, dag ins, string asm = "",
   field bit VOP3_OPSEL = 0;
 
   // Is it possible for this instruction to be atomic?
-  field bit maybeAtomic = 0;
+  field bit maybeAtomic = 1;
 
   // This bit indicates that this is a VI instruction which is renamed
   // in GFX9. Required for correct mapping from pseudo to MC.

llvm/lib/Target/AMDGPU/SIInstructions.td

@@ -111,7 +111,6 @@ def ATOMIC_FENCE : SPseudoInstSI<
   [(atomic_fence (i32 timm:$ordering), (i32 timm:$scope))],
   "ATOMIC_FENCE $ordering, $scope"> {
   let hasSideEffects = 1;
-  let maybeAtomic = 1;
 }
 
 let hasSideEffects = 0, mayLoad = 0, mayStore = 0, Uses = [EXEC] in {
@@ -563,6 +562,7 @@ def SI_MASKED_UNREACHABLE : SPseudoInstSI <(outs), (ins),
   let hasNoSchedulingInfo = 1;
   let FixedSize = 1;
   let isMeta = 1;
+  let maybeAtomic = 0;
 }
 
 // Used as an isel pseudo to directly emit initialization with an

llvm/lib/Target/AMDGPU/SMInstructions.td

@@ -29,6 +29,7 @@ class SM_Pseudo <string opName, dag outs, dag ins, string asmOps, list<dag> patt
   let mayStore = 0;
   let mayLoad = 1;
   let hasSideEffects = 0;
+  let maybeAtomic = 0;
   let UseNamedOperandTable = 1;
   let SchedRW = [WriteSMEM];