From 916f48a0547ecbda69e06a784888f8d1ffc0c0ad Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Fri, 5 Feb 2010 22:03:18 +0000 Subject: Teach SimplifyCFG about magic pointer constants. Weird code sometimes uses pointer constants other than null. This patch teaches SimplifyCFG to build switch instructions in those cases. Code like this: void f(const char *x) { if (!x) puts("null"); else if ((uintptr_t)x == 1) puts("one"); else if (x == (char*)2 || x == (char*)3) puts("two"); else if ((intptr_t)x == 4) puts("four"); else puts(x); } Now becomes a switch: define void @f(i8* %x) nounwind ssp { entry: %magicptr23 = ptrtoint i8* %x to i64 ; [#uses=1] switch i64 %magicptr23, label %if.else16 [ i64 0, label %if.then i64 1, label %if.then2 i64 2, label %if.then9 i64 3, label %if.then9 i64 4, label %if.then14 ] Note that LLVM's own DenseMap uses magic pointers. llvm-svn: 95439 --- llvm/test/Transforms/SimplifyCFG/MagicPointer.ll | 76 ++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 llvm/test/Transforms/SimplifyCFG/MagicPointer.ll (limited to 'llvm/test') diff --git a/llvm/test/Transforms/SimplifyCFG/MagicPointer.ll b/llvm/test/Transforms/SimplifyCFG/MagicPointer.ll new file mode 100644 index 00000000000..54e5b14880c --- /dev/null +++ b/llvm/test/Transforms/SimplifyCFG/MagicPointer.ll @@ -0,0 +1,76 @@ +; Test that simplifycfg can create switch instructions from constant pointers. +; +; RUN: opt < %s -simplifycfg -S | FileCheck %s + +; CHECK: switch i64 %magicptr +; CHECK: i64 0, label +; CHECK: i64 1, label +; CHECK: i64 2, label +; CHECK: i64 3, label +; CHECK: i64 4, label +; CHECK-NOT: br +; CHECK: } + +target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64" +target triple = "x86_64-apple-darwin10.0.0" + +@.str = private constant [5 x i8] c"null\00" ; <[5 x i8]*> [#uses=2] +@.str1 = private constant [4 x i8] c"one\00" ; <[4 x i8]*> [#uses=2] +@.str2 = private constant [4 x i8] c"two\00" ; <[4 x i8]*> [#uses=2] +@.str3 = private constant [5 x i8] c"four\00" ; <[5 x i8]*> [#uses=2] + +define void @f(i8* %x) nounwind ssp { +entry: + %tobool = icmp eq i8* %x, null ; [#uses=1] + br i1 %tobool, label %if.then, label %if.else + +if.then: ; preds = %entry + %call = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @.str, i64 0, i64 0)) nounwind ; [#uses=0] + br label %if.end21 + +if.else: ; preds = %entry + %cmp = icmp eq i8* %x, inttoptr (i64 1 to i8*) ; [#uses=1] + br i1 %cmp, label %if.then2, label %if.else4 + +if.then2: ; preds = %if.else + %call3 = call i32 @puts(i8* getelementptr inbounds ([4 x i8]* @.str1, i64 0, i64 0)) nounwind ; [#uses=0] + br label %if.end20 + +if.else4: ; preds = %if.else + %cmp6 = icmp eq i8* %x, inttoptr (i64 2 to i8*) ; [#uses=1] + br i1 %cmp6, label %if.then9, label %lor.lhs.false + +lor.lhs.false: ; preds = %if.else4 + %cmp8 = icmp eq i8* %x, inttoptr (i64 3 to i8*) ; [#uses=1] + br i1 %cmp8, label %if.then9, label %if.else11 + +if.then9: ; preds = %lor.lhs.false, %if.else4 + %call10 = call i32 @puts(i8* getelementptr inbounds ([4 x i8]* @.str2, i64 0, i64 0)) nounwind ; [#uses=0] + br label %if.end19 + +if.else11: ; preds = %lor.lhs.false + %cmp13 = icmp eq i8* %x, inttoptr (i64 4 to i8*) ; [#uses=1] + br i1 %cmp13, label %if.then14, label %if.else16 + +if.then14: ; preds = %if.else11 + %call15 = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @.str3, i64 0, i64 0)) nounwind ; [#uses=0] + br label %if.end + +if.else16: ; preds = %if.else11 + %call18 = call i32 @puts(i8* %x) nounwind ; [#uses=0] + br label %if.end + +if.end: ; preds = %if.else16, %if.then14 + br label %if.end19 + +if.end19: ; preds = %if.end, %if.then9 + br label %if.end20 + +if.end20: ; preds = %if.end19, %if.then2 + br label %if.end21 + +if.end21: ; preds = %if.end20, %if.then + ret void +} + +declare i32 @puts(i8*) -- cgit v1.2.3