1 files changed, 70 insertions, 0 deletions
diff --git a/test/Transforms/Reassociate/fast-SubReassociate.ll b/test/Transforms/Reassociate/fast-SubReassociate.ll
new file mode 100644
index 0000000..db4191a
--- /dev/null
+++ b/test/Transforms/Reassociate/fast-SubReassociate.ll
@@ -0,0 +1,70 @@
+; RUN: opt < %s -reassociate -constprop -instcombine -S | FileCheck %s
+
+define float @test1(float %A, float %B) {
+; CHECK-LABEL: test1
+; CHECK-NEXT: %W = fadd float %B, 5.000000e+00
+; CHECK-NEXT: %X = fadd float %A, -7.000000e+00
+; CHECK-NEXT: %Y = fsub float %X, %W
+; CHECK-NEXT: %Z = fadd float %Y, 1.200000e+01
+; CHECK-NEXT: ret float %Z
+
+  %W = fadd float 5.0, %B
+  %X = fadd float -7.0, %A
+  %Y = fsub float %X, %W
+  %Z = fadd float %Y, 12.0
+  ret float %Z
+}
+
+; With sub reassociation, constant folding can eliminate all of the constants.
+define float @test2(float %A, float %B) {
+; CHECK-LABEL: test2
+; CHECK-NEXT: %Z = fsub fast float %A, %B
+; CHECK-NEXT: ret float %Z
+
+  %W = fadd fast float %B, 5.000000e+00
+  %X = fadd fast float %A, -7.000000e+00
+  %Y = fsub fast float %X, %W
+  %Z = fadd fast float %Y, 1.200000e+01
+  ret float %Z
+
+}
+
+define float @test3(float %A, float %B, float %C, float %D) {
+; CHECK-LABEL: test3
+; CHECK-NEXT: %M = fadd float %A, 1.200000e+01
+; CHECK-NEXT: %N = fadd float %M, %B
+; CHECK-NEXT: %O = fadd float %N, %C
+; CHECK-NEXT: %P = fsub float %D, %O
+; CHECK-NEXT: %Q = fadd float %P, 1.200000e+01
+; CHECK-NEXT: ret float %Q
+
+  %M = fadd float %A, 1.200000e+01
+  %N = fadd float %M, %B
+  %O = fadd float %N, %C
+  %P = fsub float %D, %O
+  %Q = fadd float %P, 1.200000e+01
+  ret float %Q
+}
+
+; With sub reassociation, constant folding can eliminate the two 12 constants.
+define float @test4(float %A, float %B, float %C, float %D) {
+; CHECK-LABEL: test4
+; CHECK-NEXT: %B.neg = fsub fast float -0.000000e+00, %B
+; CHECK-NEXT: %O.neg = fsub fast float %B.neg, %A
+; CHECK-NEXT: %P = fsub fast float %O.neg, %C
+; CHECK-NEXT: %Q = fadd fast float %P, %D
+; CHECK-NEXT: ret float %Q
+
+; FIXME: InstCombine should be able to get us to the following:
+; %sum = fadd fast float %B, %A
+; %sum1 = fadd fast float %sum, %C
+; %Q = fsub fast float %D, %sum1
+; ret i32 %Q
+
+  %M = fadd fast float 1.200000e+01, %A
+  %N = fadd fast float %M, %B
+  %O = fadd fast float %N, %C
+  %P = fsub fast float %D, %O
+  %Q = fadd fast float 1.200000e+01, %P
+  ret float %Q
+}