[ARM] ParallelDSP: only support i16 loads for now

We were miscompiling i8 loads, so reject them as unsupported narrow operations
for now.

Differential Revision: https://reviews.llvm.org/D48944

llvm-svn: 336319
diff --git a/llvm/test/CodeGen/ARM/smlad1.ll b/llvm/test/CodeGen/ARM/smlad1.ll
index dc3fa8b..5a504ec 100644
--- a/llvm/test/CodeGen/ARM/smlad1.ll
+++ b/llvm/test/CodeGen/ARM/smlad1.ll
@@ -1,5 +1,6 @@
 ; RUN: opt -mtriple=arm-arm-eabi -mcpu=cortex-m33 < %s -parallel-dsp -S | FileCheck %s
 
+; CHECK-LABEL: @test1
 ; CHECK:  %mac1{{\.}}026 = phi i32 [ [[V8:%[0-9]+]], %for.body ], [ 0, %for.body.preheader ]
 ; CHECK:  [[V4:%[0-9]+]] = bitcast i16* %arrayidx3 to i32*
 ; CHECK:  [[V5:%[0-9]+]] = load i32, i32* [[V4]], align 2
@@ -7,7 +8,7 @@
 ; CHECK:  [[V7:%[0-9]+]] = load i32, i32* [[V6]], align 2
 ; CHECK:  [[V8]] = call i32 @llvm.arm.smlad(i32 [[V5]], i32 [[V7]], i32 %mac1{{\.}}026)
 
-define dso_local i32 @test(i32 %arg, i32* nocapture readnone %arg1, i16* nocapture readonly %arg2, i16* nocapture readonly %arg3) {
+define dso_local i32 @test1(i32 %arg, i32* nocapture readnone %arg1, i16* nocapture readonly %arg2, i16* nocapture readonly %arg3) {
 entry:
   %cmp24 = icmp sgt i32 %arg, 0
   br i1 %cmp24, label %for.body.preheader, label %for.cond.cleanup
@@ -48,3 +49,47 @@
   br i1 %exitcond, label %for.body, label %for.cond.cleanup
 }
 
+; Here we have i8 loads, which we do want to support, but don't handle yet.
+;
+; CHECK-LABEL: @test2
+; CHECK-NOT:   call i32 @llvm.arm.smlad
+;
+define dso_local i32 @test2(i32 %arg, i32* nocapture readnone %arg1, i8* nocapture readonly %arg2, i8* nocapture readonly %arg3) {
+entry:
+  %cmp24 = icmp sgt i32 %arg, 0
+  br i1 %cmp24, label %for.body.preheader, label %for.cond.cleanup
+
+for.body.preheader:
+  %.pre = load i8, i8* %arg3, align 2
+  %.pre27 = load i8, i8* %arg2, align 2
+  br label %for.body
+
+for.cond.cleanup:
+  %mac1.0.lcssa = phi i32 [ 0, %entry ], [ %add11, %for.body ]
+  ret i32 %mac1.0.lcssa
+
+for.body:
+  %mac1.026 = phi i32 [ %add11, %for.body ], [ 0, %for.body.preheader ]
+  %i.025 = phi i32 [ %add, %for.body ], [ 0, %for.body.preheader ]
+  %arrayidx = getelementptr inbounds i8, i8* %arg3, i32 %i.025
+  %0 = load i8, i8* %arrayidx, align 2
+  %add = add nuw nsw i32 %i.025, 1
+  %arrayidx1 = getelementptr inbounds i8, i8* %arg3, i32 %add
+  %1 = load i8, i8* %arrayidx1, align 2
+  %arrayidx3 = getelementptr inbounds i8, i8* %arg2, i32 %i.025
+  %2 = load i8, i8* %arrayidx3, align 2
+  %conv = sext i8 %2 to i32
+  %conv4 = sext i8 %0 to i32
+  %mul = mul nsw i32 %conv, %conv4
+  %arrayidx6 = getelementptr inbounds i8, i8* %arg2, i32 %add
+  %3 = load i8, i8* %arrayidx6, align 2
+  %conv7 = sext i8 %3 to i32
+  %conv8 = sext i8 %1 to i32
+  %mul9 = mul nsw i32 %conv7, %conv8
+  %add10 = add i32 %mul, %mac1.026
+  %add11 = add i32 %add10, %mul9
+  %exitcond = icmp ne i32 %add, %arg
+  br i1 %exitcond, label %for.body, label %for.cond.cleanup
+}
+
+