commit a6beac1accd9222e4567bca8c3000e87303d6204
author Matheus Almeida <matheus.almeida@imgtec.com> Thu Dec 05 12:07:05 2013 +0000
committer Matheus Almeida <matheus.almeida@imgtec.com> Thu Dec 05 12:07:05 2013 +0000
tree 898c9b69c3587690f8d4d0d860a0d66e82dcf280
parent 9be70fbda9e3efbb33a285f600e13c16d41f59e1

[mips] Small code generation improvement for conditional operator (select)
in case the operands are constants and its difference is |1|.
It should be possible in those cases to rematerialize the result using
MIPS's slt and similar instructions.

The small update to some of the tests in cmov.ll, sel1c.ll and sel2c.ll was needed
otherwise the optimization implemented in this patch would have been triggered
(difference between the operands was 1) and that would have changed the semantic
of the tests.

llvm-svn: 196498

llvm/test/CodeGen/Mips/cmov.ll

diff --git a/llvm/test/CodeGen/Mips/cmov.ll b/llvm/test/CodeGen/Mips/cmov.ll
index c24c5ac..f2009fa 100644
--- a/llvm/test/CodeGen/Mips/cmov.ll
+++ b/llvm/test/CodeGen/Mips/cmov.ll
@@ -74,7 +74,7 @@
 define i32 @slti0(i32 %a) {
 entry:
   %cmp = icmp sgt i32 %a, 32766
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -84,7 +84,7 @@
 define i32 @slti1(i32 %a) {
 entry:
   %cmp = icmp sgt i32 %a, 32767
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -95,7 +95,7 @@
 define i32 @slti2(i32 %a) {
 entry:
   %cmp = icmp sgt i32 %a, -32769
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -105,7 +105,7 @@
 define i32 @slti3(i32 %a) {
 entry:
   %cmp = icmp sgt i32 %a, -32770
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -162,7 +162,7 @@
 define i32 @sltiu0(i32 %a) {
 entry:
   %cmp = icmp ugt i32 %a, 32766
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -172,7 +172,7 @@
 define i32 @sltiu1(i32 %a) {
 entry:
   %cmp = icmp ugt i32 %a, 32767
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -183,7 +183,7 @@
 define i32 @sltiu2(i32 %a) {
 entry:
   %cmp = icmp ugt i32 %a, -32769
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
 
@@ -193,6 +193,49 @@
 define i32 @sltiu3(i32 %a) {
 entry:
   %cmp = icmp ugt i32 %a, -32770
-  %cond = select i1 %cmp, i32 3, i32 4
+  %cond = select i1 %cmp, i32 3, i32 5
   ret i32 %cond
 }
+
+; Check if
+;  (select (setxx a, N), x, x-1) or
+;  (select (setxx a, N), x-1, x)
+; doesn't generate conditional moves
+; for constant operands whose difference is |1|
+
+define i32 @slti4(i32 %a) nounwind readnone {
+  %1 = icmp slt i32 %a, 7
+  %2 = select i1 %1, i32 4, i32 3
+  ret i32 %2
+}
+
+; O32-LABEL: slti4:
+; O32-DAG: slti [[R1:\$[0-9]+]], $4, 7
+; O32-DAG: addiu [[R2:\$[0-9]+]], [[R1]], 3
+; O32-NOT: movn
+; O32:.size slti4
+
+define i32 @slti5(i32 %a) nounwind readnone {
+  %1 = icmp slt i32 %a, 7
+  %2 = select i1 %1, i32 -3, i32 -4
+  ret i32 %2
+}
+
+; O32-LABEL: slti5:
+; O32-DAG: slti [[R1:\$[0-9]+]], $4, 7
+; O32-DAG: addiu [[R3:\$[0-9]+]], [[R2:\$[a-z0-9]+]], -4
+; O32-NOT: movn
+; O32:.size slti5
+
+define i32 @slti6(i32 %a) nounwind readnone {
+  %1 = icmp slt i32 %a, 7
+  %2 = select i1 %1, i32 3, i32 4
+  ret i32 %2
+}
+
+; O32-LABEL: slti6:
+; O32-DAG: slti [[R1:\$[0-9]+]], $4, 7
+; O32-DAG: xori [[R1]], [[R1]], 1
+; O32-DAG: addiu [[R2:\$[0-9]+]], [[R1]], 3
+; O32-NOT: movn
+; O32:.size slti6
\ No newline at end of file