Generate better two address code by using commutativity

tests_lit/llvm2ice_tests/commutativity.ll

+; Test the lowering sequence for commutative operations.  If there is a source
+; operand whose lifetime ends in an operation, it should be the first operand,
+; eliminating the need for a move to start the new lifetime.
+
+; RUN: %if --need=target_X8632 --command %p2i --filetype=obj --disassemble \
+; RUN:   --target x8632 -i %s --args -O2 \
+; RUN:   | %if --need=target_X8632 --command FileCheck %s
+
+define i32 @integerAddLeft(i32 %a, i32 %b) {
+entry:
+  %tmp = add i32 %a, %b
+  %result = add i32 %a, %tmp
+  ret i32 %result
+}
+; CHECK-LABEL: integerAddLeft
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: add {{e..}},{{e..}}
+; CHECK-NEXT: add {{e..}},{{e..}}
+
+define i32 @integerAddRight(i32 %a, i32 %b) {
+entry:
+  %tmp = add i32 %a, %b
+  %result = add i32 %b, %tmp
+  ret i32 %result
+}
+; CHECK-LABEL: integerAddRight
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: add {{e..}},{{e..}}
+; CHECK-NEXT: add {{e..}},{{e..}}
+
+define i32 @integerMultiplyLeft(i32 %a, i32 %b) {
+entry:
+  %tmp = mul i32 %a, %b
+  %result = mul i32 %a, %tmp
+  ret i32 %result
+}
+; CHECK-LABEL: integerMultiplyLeft
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: imul {{e..}},{{e..}}
+; CHECK-NEXT: imul {{e..}},{{e..}}
+
+define i32 @integerMultiplyRight(i32 %a, i32 %b) {
+entry:
+  %tmp = mul i32 %a, %b
+  %result = mul i32 %b, %tmp
+  ret i32 %result
+}
+; CHECK-LABEL: integerMultiplyRight
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: mov {{e..}},DWORD PTR
+; CHECK-NEXT: imul {{e..}},{{e..}}
+; CHECK-NEXT: imul {{e..}},{{e..}}
+
+define float @floatAddLeft(float %a, float %b) {
+entry:
+  %tmp = fadd float %a, %b
+  %result = fadd float %a, %tmp
+  ret float %result
+}
+; CHECK-LABEL: floatAddLeft
+; CHECK-NEXT: movss xmm0,DWORD PTR
+; CHECK-NEXT: movss xmm1,DWORD PTR
+; CHECK-NEXT: addss xmm1,xmm0
+; CHECK-NEXT: addss xmm0,xmm1
+
+define float @floatAddRight(float %a, float %b) {
+entry:
+  %tmp = fadd float %a, %b
+  %result = fadd float %b, %tmp
+  ret float %result
+}
+; CHECK-LABEL: floatAddRight
+; CHECK-NEXT: movss xmm0,DWORD PTR
+; CHECK-NEXT: movss xmm1,DWORD PTR
+; CHECK-NEXT: addss xmm0,xmm1
+; CHECK-NEXT: addss xmm1,xmm0
+
+define float @floatMultiplyLeft(float %a, float %b) {
+entry:
+  %tmp = fmul float %a, %b
+  %result = fmul float %a, %tmp
+  ret float %result
+}
+; CHECK-LABEL: floatMultiplyLeft
+; CHECK-NEXT: movss xmm0,DWORD PTR
+; CHECK-NEXT: movss xmm1,DWORD PTR
+; CHECK-NEXT: mulss xmm1,xmm0
+; CHECK-NEXT: mulss xmm0,xmm1
+
+define float @floatMultiplyRight(float %a, float %b) {
+entry:
+  %tmp = fmul float %a, %b
+  %result = fmul float %b, %tmp
+  ret float %result
+}
+; CHECK-LABEL: floatMultiplyRight
+; CHECK-NEXT: movss xmm0,DWORD PTR
+; CHECK-NEXT: movss xmm1,DWORD PTR
+; CHECK-NEXT: mulss xmm0,xmm1
+; CHECK-NEXT: mulss xmm1,xmm0