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| -rw-r--r-- | lib/Target/README.txt | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index 69da35f1c7..080ea42dcc 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -1665,3 +1665,54 @@ int foo() { //===---------------------------------------------------------------------===// +Missed instcombine transformation: +define i1 @a(i32 %x) nounwind readnone { +entry: + %cmp = icmp eq i32 %x, 30 + %sub = add i32 %x, -30 + %cmp2 = icmp ugt i32 %sub, 9 + %or = or i1 %cmp, %cmp2 + ret i1 %or +} +This should be optimized to a single compare. Testcase derived from gcc. + +//===---------------------------------------------------------------------===// + +Missed instcombine transformation: +void b(); +void a(int x) { if (((1<<x)&8)==0) b(); } + +The shift should be optimized out. Testcase derived from gcc. + +//===---------------------------------------------------------------------===// + +Missed instcombine or reassociate transformation: +int a(int a, int b) { return (a==12)&(b>47)&(b<58); } + +The sgt and slt should be combined into a single comparison. Testcase derived +from gcc. + +//===---------------------------------------------------------------------===// + +Missed instcombine transformation: +define i32 @a(i32 %x) nounwind readnone { +entry: + %shr = lshr i32 %x, 5 ; <i32> [#uses=1] + %xor = xor i32 %shr, 67108864 ; <i32> [#uses=1] + %sub = add i32 %xor, -67108864 ; <i32> [#uses=1] + ret i32 %sub +} + +This function is equivalent to "ashr i32 %x, 5". Testcase derived from gcc. + +//===---------------------------------------------------------------------===// + +isSafeToLoadUnconditionally should allow a GEP of a global/alloca with constant +indicies within the bounds of the allocated object. Reduced example: + +const int a[] = {3,6}; +int b(int y) { int* x = y ? &a[0] : &a[1]; return *x; } + +All the loads should be eliminated. Testcase derived from gcc. + +//===---------------------------------------------------------------------===// |