[ARM] Typesize lower bound for ARMCodeGenPrepare

[samparker]

Summary

We only try to promote types with are smaller than 16-bits, but we also need to check that the type is not less than 8-bits.

[SjoerdMeijer]

Looks like a straightforward fix to me.

llvm/trunk/lib/Target/ARM/ARMCodeGenPrepare.cpp

for (auto &Op : I->operands()) {
     }
   }
   return true;
 }
 
 bool ARMCodeGenPrepare::TryToPromote(Value *V) {
   OrigTy = V->getType();
   TypeSize = OrigTy->getPrimitiveSizeInBits();
-  if (TypeSize > 16)
+  if (TypeSize > 16 || TypeSize < 8)
     return false;
 
   if (!isSupportedValue(V) || !shouldPromote(V) || !isLegalToPromote(V))
     return false;
 
   LLVM_DEBUG(dbgs() << "ARM CGP: TryToPromote: " << *V << ", TypeSize = "
              << TypeSize << "\n");
 

llvm/trunk/test/CodeGen/ARM/arm-cgp-icmps.ll

 ; CHECK-COMMON: cmp r2, r1
 define i32 @icmp_not(i16 zeroext %arg0, i16 zeroext %arg1) {
   %not = xor i16 %arg0, -1
   %cmp = icmp eq i16 %not, %arg1
   %res = select i1 %cmp, i32 16, i32 32
   ret i32 %res
 }
 
+; CHECK-COMMON-LABEL: icmp_i1
+; CHECK-NOT: uxt
+define i32 @icmp_i1(i1* %arg0, i1 zeroext %arg1, i32 %a, i32 %b) {
+entry:
+  %load = load i1, i1* %arg0
+  %not = xor i1 %load, 1
+  %cmp = icmp eq i1 %arg1, %not
+  %res = select i1 %cmp, i32 %a, i32 %b
+  ret i32 %res
+}
+
+; CHECK-COMMON-LABEL: icmp_i7
+; CHECK-COMMON: ldrb
+; CHECK-COMMON: and
+; CHECK-COMMON: cmp
+define i32 @icmp_i7(i7* %arg0, i7 zeroext %arg1, i32 %a, i32 %b) {
+entry:
+  %load = load i7, i7* %arg0
+  %add = add nuw i7 %load, 1
+  %cmp = icmp ult i7 %arg1, %add
+  %res = select i1 %cmp, i32 %a, i32 %b
+  ret i32 %res
+}
+