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add a missed bitfield instcombine.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130137 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2011-04-25 18:44:26 +00:00
parent f48eb533d5
commit ed0318eab8
1 changed files with 47 additions and 0 deletions
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47
lib/Target/README.txt
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@ -2305,3 +2305,50 @@ Not having this is blocking resolving PR6627.
//===---------------------------------------------------------------------===//
This code:
typedef struct {
int f1:1;
int f2:1;
int f3:1;
int f4:29;
} t1;
typedef struct {
int f1:1;
int f2:1;
int f3:30;
} t2;
t1 s1;
t2 s2;
void func1(void)
{
s1.f1 = s2.f1;
s1.f2 = s2.f2;
}
Compiles into this IR (on x86-64 at least):
%struct.t1 = type { i8, [3 x i8] }
@s2 = global %struct.t1 zeroinitializer, align 4
@s1 = global %struct.t1 zeroinitializer, align 4
define void @func1() nounwind ssp noredzone {
entry:
%0 = load i32* bitcast (%struct.t1* @s2 to i32*), align 4
%bf.val.sext5 = and i32 %0, 1
%1 = load i32* bitcast (%struct.t1* @s1 to i32*), align 4
%2 = and i32 %1, -4
%3 = or i32 %2, %bf.val.sext5
%bf.val.sext26 = and i32 %0, 2
%4 = or i32 %3, %bf.val.sext26
store i32 %4, i32* bitcast (%struct.t1* @s1 to i32*), align 4
ret void
}
The two or/and's should be merged into one each.
//===---------------------------------------------------------------------===//