[ARM] Parallel DSP Pass
Armv6 introduced instructions to perform 32-bit SIMD operations. The purpose of
this pass is to do some straightforward IR pattern matching to create ACLE DSP
intrinsics, which map on these 32-bit SIMD operations.
Currently, only the SMLAD instruction gets recognised. This instruction
performs two multiplications with 16-bit operands, and stores the result in an
accumulator. We will follow this up with patches to recognise SMLAD in more
cases, and also to generate other DSP instructions (like e.g. SADD16).
Patch by: Sam Parker and Sjoerd Meijer
Differential Revision: https://reviews.llvm.org/D48128
llvm-svn: 335850
diff --git a/llvm/test/CodeGen/ARM/smlad2.ll b/llvm/test/CodeGen/ARM/smlad2.ll
new file mode 100644
index 0000000..219b55c
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/smlad2.ll
@@ -0,0 +1,52 @@
+; RUN: opt -mtriple=arm-arm-eabi -mcpu=cortex-m33 < %s -parallel-dsp -S | FileCheck %s
+;
+; Operands of both muls are not symmetrical (see also comments inlined below), check
+; that the rewrite isn't triggered.
+;
+; CHECK-NOT: call i32 @llvm.arm.smlad
+;
+define dso_local i32 @test(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
+
+for.body.preheader:
+ %.pre = load i16, i16* %arg3, align 2
+ %.pre27 = load i16, i16* %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 i16, i16* %arg3, i32 %i.025
+ %0 = load i16, i16* %arrayidx, align 2
+ %add = add nuw nsw i32 %i.025, 1
+ %arrayidx1 = getelementptr inbounds i16, i16* %arg3, i32 %add
+ %1 = load i16, i16* %arrayidx1, align 2
+ %arrayidx3 = getelementptr inbounds i16, i16* %arg2, i32 %i.025
+ %2 = load i16, i16* %arrayidx3, align 2
+ %conv = sext i16 %2 to i32
+
+; This zero-extends the 2nd operand of %mul:
+ %conv4 = zext i16 %0 to i32
+
+ %mul = mul nsw i32 %conv, %conv4
+ %arrayidx6 = getelementptr inbounds i16, i16* %arg2, i32 %add
+ %3 = load i16, i16* %arrayidx6, align 2
+
+; And here we only have sign-extensions. Thus, the operands of
+; %mul and %mul9 are not symmetrical:
+ %conv7 = sext i16 %3 to i32
+ %conv8 = sext i16 %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
+}
+