[PowerPC] Better lowering for add/or of a FrameIndex
If we have an add (or an or that is really an add), where one operand is a
FrameIndex and the other operand is a small constant, we can combine the
lowering of the FrameIndex (which is lowered as an add of the FI and a zero
offset) with the constant operand.
Amusingly, this is an old potential improvement entry from
lib/Target/PowerPC/README.txt which had never been resolved. In short, we used
to lower:
%X = alloca { i32, i32 }
%Y = getelementptr {i32,i32}* %X, i32 0, i32 1
ret i32* %Y
as:
addi 3, 1, -8
ori 3, 3, 4
blr
and now we produce:
addi 3, 1, -4
blr
which is much more sensible.
llvm-svn: 224071
diff --git a/llvm/test/CodeGen/PowerPC/add-fi.ll b/llvm/test/CodeGen/PowerPC/add-fi.ll
new file mode 100644
index 0000000..18892c8
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/add-fi.ll
@@ -0,0 +1,24 @@
+; RUN: llc -mcpu=ppc64 < %s | FileCheck %s
+target datalayout = "E-m:e-i64:64-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+define i32* @test1() {
+ %X = alloca { i32, i32 }
+ %Y = getelementptr {i32,i32}* %X, i32 0, i32 1
+ ret i32* %Y
+
+; CHECK-LABEL: @test1
+; CHECK: addi 3, 1, -4
+; CHECK: blr
+}
+
+define i32* @test2() {
+ %X = alloca { i32, i32, i32, i32 }
+ %Y = getelementptr {i32,i32,i32,i32}* %X, i32 0, i32 3
+ ret i32* %Y
+
+; CHECK-LABEL: @test2
+; CHECK: addi 3, 1, -4
+; CHECK: blr
+}
+