Don't try to simplify urem and srem using arithmetic rules that don't work

under modulo (overflow). Fixes PR1933.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47987 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 33 insertions, 26 deletions

diff --git a/test/Transforms/InstCombine/rem.ll b/test/Transforms/InstCombine/rem.ll
index c0e0fa4dc3..8b2263d9b2 100644
--- a/test/Transforms/InstCombine/rem.ll
+++ b/test/Transforms/InstCombine/rem.ll
@@ -1,76 +1,83 @@
 ; This test makes sure that these instructions are properly eliminated.
 ;
 ; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep rem
+; END.
 
 define i32 @test1(i32 %A) {
-	%B = srem i32 %A, 1		; <i32> [#uses=1]
+	%B = srem i32 %A, 1	; ISA constant 0
 	ret i32 %B
 }
 
-define i32 @test2(i32 %A) {
-	%B = srem i32 0, %A		; <i32> [#uses=1]
+define i32 @test2(i32 %A) {	; 0 % X = 0, we don't need to preserve traps
+	%B = srem i32 0, %A
 	ret i32 %B
 }
 
 define i32 @test3(i32 %A) {
-	%B = urem i32 %A, 8		; <i32> [#uses=1]
+	%B = urem i32 %A, 8
 	ret i32 %B
 }
 
 define i1 @test3a(i32 %A) {
-	%B = srem i32 %A, -8		; <i32> [#uses=1]
-	%C = icmp ne i32 %B, 0		; <i1> [#uses=1]
+	%B = srem i32 %A, -8
+	%C = icmp ne i32 %B, 0
 	ret i1 %C
 }
 
 define i32 @test4(i32 %X, i1 %C) {
-	%V = select i1 %C, i32 1, i32 8		; <i32> [#uses=1]
-	%R = urem i32 %X, %V		; <i32> [#uses=1]
+	%V = select i1 %C, i32 1, i32 8
+	%R = urem i32 %X, %V
 	ret i32 %R
 }
 
 define i32 @test5(i32 %X, i8 %B) {
-	%shift.upgrd.1 = zext i8 %B to i32		; <i32> [#uses=1]
-	%Amt = shl i32 32, %shift.upgrd.1		; <i32> [#uses=1]
-	%V = urem i32 %X, %Amt		; <i32> [#uses=1]
+	%shift.upgrd.1 = zext i8 %B to i32
+	%Amt = shl i32 32, %shift.upgrd.1
+	%V = urem i32 %X, %Amt
 	ret i32 %V
 }
 
 define i32 @test6(i32 %A) {
-	%B = srem i32 %A, 0		; <i32> [#uses=1]
+	%B = srem i32 %A, 0	;; undef
 	ret i32 %B
 }
 
 define i32 @test7(i32 %A) {
-	%B = mul i32 %A, 26		; <i32> [#uses=1]
-	%C = srem i32 %B, 13		; <i32> [#uses=1]
+	%B = mul i32 %A, 8
+	%C = srem i32 %B, 4
 	ret i32 %C
 }
 
 define i32 @test8(i32 %A) {
-	%B = shl i32 %A, 4		; <i32> [#uses=1]
-	%C = srem i32 %B, 8		; <i32> [#uses=1]
+	%B = shl i32 %A, 4
+	%C = srem i32 %B, 8
 	ret i32 %C
 }
 
 define i32 @test9(i32 %A) {
-	%B = mul i32 %A, 124		; <i32> [#uses=1]
-	%C = urem i32 %B, 62		; <i32> [#uses=1]
+	%B = mul i32 %A, 64
+	%C = urem i32 %B, 32
 	ret i32 %C
 }
 
 define i32 @test10(i8 %c) {
-	%tmp.1 = zext i8 %c to i32		; <i32> [#uses=1]
-	%tmp.2 = mul i32 %tmp.1, 3		; <i32> [#uses=1]
-	%tmp.3 = sext i32 %tmp.2 to i64		; <i64> [#uses=1]
-	%tmp.5 = urem i64 %tmp.3, 3		; <i64> [#uses=1]
-	%tmp.6 = trunc i64 %tmp.5 to i32		; <i32> [#uses=1]
+	%tmp.1 = zext i8 %c to i32
+	%tmp.2 = mul i32 %tmp.1, 4
+	%tmp.3 = sext i32 %tmp.2 to i64
+	%tmp.5 = urem i64 %tmp.3, 4
+	%tmp.6 = trunc i64 %tmp.5 to i32
 	ret i32 %tmp.6
 }
 
 define i32 @test11(i32 %i) {
-	%tmp.1 = and i32 %i, -2		; <i32> [#uses=1]
-	%tmp.3 = mul i32 %tmp.1, 3		; <i32> [#uses=1]
-	%tmp.5 = srem i32 %tmp.3, 6		; <i32> [#uses=1]
+	%tmp.1 = and i32 %i, -2
+	%tmp.3 = mul i32 %tmp.1, 2
+	%tmp.5 = urem i32 %tmp.3, 4
+	ret i32 %tmp.5
+}
+
+define i32 @test12(i32 %i) {
+	%tmp.1 = and i32 %i, -4
+	%tmp.5 = srem i32 %tmp.1, 2
 	ret i32 %tmp.5
 }