[EVM] Prefer to emit PUSH0 over a DUP

Prefer to emit PUSH0 instead of DUP, as it is cheaper.

Signed-off-by: Vladimir Radosavljevic <[email protected]>

Author: vladimirradosavljevic

llvm/lib/Target/EVM/EVMStackifyCodeEmitter.cpp

@@ -408,6 +408,13 @@ void EVMStackifyCodeEmitter::emitStackPermutations(const Stack &TargetStack) {
       [&](const StackSlot *Slot) {
         assert(CurrentStack.size() == Emitter.stackHeight());
 
+        // Prefer to emit PUSH0 instead of DUP, as it is cheaper.
+        if (isa<LiteralSlot>(Slot) &&
+            cast<LiteralSlot>(Slot)->getValue().isZero()) {
+          Emitter.emitConstant(0);
+          return;
+        }
+
         // Dup the slot, if already on stack and reachable.
         auto SlotIt = llvm::find(llvm::reverse(CurrentStack), Slot);
         if (SlotIt != CurrentStack.rend()) {

llvm/test/CodeGen/EVM/bps-recursive-func-compress-stack.mir

@@ -140,7 +140,7 @@ body:             |
     ; CHECK-NEXT: POP_S
     ; CHECK-NEXT: POP_S
     ; CHECK-NEXT: PUSH0_S
-    ; CHECK-NEXT: DUP1_S
+    ; CHECK-NEXT: PUSH0_S
     ; CHECK-NEXT: SSTORE_S
     ; CHECK-NEXT: DUP7_S
     ; CHECK-NEXT: SSTORE_S
@@ -168,19 +168,19 @@ body:             |
     ; CHECK-NEXT: SSTORE_S
     ; CHECK-NEXT: PUSH_LABEL <mcsymbol >
     ; CHECK-NEXT: PUSH0_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
-    ; CHECK-NEXT: DUP1_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
+    ; CHECK-NEXT: PUSH0_S
     ; CHECK-NEXT: PseudoCALL @_testRemoveAndInsertBack_rt_707, <mcsymbol >
     ; CHECK-NEXT: PseudoRET
     %3:gpr = ARGUMENT 0, implicit $arguments

llvm/test/CodeGen/EVM/bps-spills-1.mir

@@ -614,7 +614,7 @@ body:             |
   ; CHECK-NEXT:   liveins: $value_stack
   ; CHECK-NEXT: {{  $}}
   ; CHECK-NEXT:   PUSH0_S
-  ; CHECK-NEXT:   DUP1_S
+  ; CHECK-NEXT:   PUSH0_S
   ; CHECK-NEXT:   SWAP2_S
   ; CHECK-NEXT:   EQ_S
   ; CHECK-NEXT:   PseudoJUMPI %bb.35

llvm/test/CodeGen/EVM/no-small-constant-unfolding.ll

@@ -15,7 +15,7 @@ define void @test1() #1 {
 ; CHECK:       ; %bb.0: ; %entry
 ; CHECK-NEXT:    JUMPDEST
 ; CHECK-NEXT:    PUSH0
-; CHECK-NEXT:    DUP1
+; CHECK-NEXT:    PUSH0
 ; CHECK-NEXT:    RETURN
 entry:
   tail call void @llvm.evm.return(ptr addrspace(1) null, i256 0)

llvm/test/CodeGen/EVM/push0-over-dup.ll

@@ -9,7 +9,7 @@ define { i256, i256 } @test() {
 ; CHECK:       ; %bb.0:
 ; CHECK-NEXT:    JUMPDEST
 ; CHECK-NEXT:    PUSH0
-; CHECK-NEXT:    DUP1
+; CHECK-NEXT:    PUSH0
 ; CHECK-NEXT:    SWAP2
 ; CHECK-NEXT:    JUMP
   ret { i256, i256 } zeroinitializer