Teach the table lookup optimization to generate range compares

when a consequtive sequence of elements all satisfies the 
predicate.  Like the double compare case, this generates better
code than the magic constant case and generalizes to more than
32/64 element array lookups.

Here are some examples where it triggers.  From 403.gcc, most
accesses to the rtx_class array are handled, e.g.:

@rtx_class = constant [153 x i8] c"xxxxxmmmmmmmmxxxxxxxxxxxxmxxxxxxiiixxxxxxxxxxxxxxxxxxxooxooooooxxoooooox3x2c21c2222ccc122222ccccaaaaaa<<<<<<<<<<<<<<<<<<111111111111bbooxxxxxxxxxxcc2211x", align 32 ; <[153 x i8]*> [#uses=547]
   %142 = icmp eq i8 %141, 105
@rtx_class = constant [153 x i8] c"xxxxxmmmmmmmmxxxxxxxxxxxxmxxxxxxiiixxxxxxxxxxxxxxxxxxxooxooooooxxoooooox3x2c21c2222ccc122222ccccaaaaaa<<<<<<<<<<<<<<<<<<111111111111bbooxxxxxxxxxxcc2211x", align 32 ; <[153 x i8]*> [#uses=543]
	   %165 = icmp eq i8 %164, 60      

Also, most of the 59-element arrays (mode_class/rid_to_yy, etc) 
optimized before are actually range compares.  This lets 32-bit
machines optimize them.

400.perlbmk has stuff like this:

400.perlbmk: PL_regkind, even for 32-bit:
@PL_regkind = constant [62 x i8] c"\00\00\02\02\02\06\06\06\06\09\09\0B\0B\0D\0E\0E\0E\11\12\12\14\14\16\16\18\18\1A\1A\1C\1C\1E\1F !!!$$&'((((,-.///88886789:;8$", align 32 ; <[62 x i8]*> [#uses=4]
	   %811 = icmp ne i8 %810, 33 

@PL_utf8skip = constant [256 x i8] c"\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\03\03\03\03\03\03\03\03\03\03\03\03\03\03\03\03\04\04\04\04\04\04\04\04\05\05\05\05\06\06\07\0D", align 32 ; <[256 x i8]*> [#uses=94]
	   %12 = icmp ult i8 %10, 2
           
etc.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92426 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 3 deletions

diff --git a/test/Transforms/InstCombine/load-cmp.ll b/test/Transforms/InstCombine/load-cmp.ll
index fabafed..69e13cb 100644
--- a/test/Transforms/InstCombine/load-cmp.ll
+++ b/test/Transforms/InstCombine/load-cmp.ll
@@ -2,7 +2,8 @@
 
 @G16 = internal constant [10 x i16] [i16 35, i16 82, i16 69, i16 81, i16 85, 
                                      i16 73, i16 82, i16 69, i16 68, i16 0]
-@GD = internal constant [3 x double] [double 1.0, double 4.0, double -20.0]
+@GD = internal constant [6 x double]
+   [double -10.0, double 1.0, double 4.0, double 2.0, double -20.0, double -40.0]
 
 define i1 @test1(i32 %X) {
   %P = getelementptr [10 x i16]* @G16, i32 0, i32 %X
@@ -25,12 +26,12 @@ define i1 @test2(i32 %X) {
 }
 
 define i1 @test3(i32 %X) {
-  %P = getelementptr [3 x double]* @GD, i32 0, i32 %X
+  %P = getelementptr [6 x double]* @GD, i32 0, i32 %X
   %Q = load double* %P
   %R = fcmp oeq double %Q, 1.0
   ret i1 %R
 ; CHECK: @test3
-; CHECK-NEXT: %R = icmp eq i32 %X, 0
+; CHECK-NEXT: %R = icmp eq i32 %X, 1
 ; CHECK-NEXT: ret i1 %R
 }
 
@@ -57,3 +58,25 @@ define i1 @test5(i32 %X) {
 ; CHECK-NEXT: %R = or i1
 ; CHECK-NEXT: ret i1 %R
 }
+
+define i1 @test6(i32 %X) {
+  %P = getelementptr [6 x double]* @GD, i32 0, i32 %X
+  %Q = load double* %P
+  %R = fcmp ogt double %Q, 0.0
+  ret i1 %R
+; CHECK: @test6
+; CHECK-NEXT: add i32 %X, -1
+; CHECK-NEXT: %R = icmp ult i32 {{.*}}, 3
+; CHECK-NEXT: ret i1 %R
+}
+
+define i1 @test7(i32 %X) {
+  %P = getelementptr [6 x double]* @GD, i32 0, i32 %X
+  %Q = load double* %P
+  %R = fcmp olt double %Q, 0.0
+  ret i1 %R
+; CHECK: @test7
+; CHECK-NEXT: add i32 %X, -1
+; CHECK-NEXT: %R = icmp ugt i32 {{.*}}, 2
+; CHECK-NEXT: ret i1 %R
+}