1; RUN: llc -mtriple=armv7-none-eabi -mattr=+neon < %s -o - | FileCheck %s 2 3; The following functions test the use case where an X constraint is used to 4; add a dependency between an assembly instruction (vmsr in this case) and 5; another instruction. In each function, we use a different type for the 6; X constraint argument. 7; 8; We can something similar from the following C code: 9; double f1(double f, int pscr_value) { 10; asm volatile("vmsr fpscr,%0" : "=X" ((f)): "r" (pscr_value)); 11; return f+f; 12; } 13 14; CHECK-LABEL: f1 15; CHECK: vmsr fpscr 16; CHECK: vadd.f64 17 18define arm_aapcs_vfpcc double @f1(double %f, i32 %pscr_value) { 19entry: 20 %f.addr = alloca double, align 8 21 store double %f, double* %f.addr, align 8 22 call void asm sideeffect "vmsr fpscr,$1", "=*X,r"(double* nonnull %f.addr, i32 %pscr_value) nounwind 23 %0 = load double, double* %f.addr, align 8 24 %add = fadd double %0, %0 25 ret double %add 26} 27 28; int f2(int f, int pscr_value) { 29; asm volatile("vmsr fpscr,%0" : "=X" ((f)): "r" (pscr_value)); 30; return f+f; 31; } 32 33; CHECK-LABEL: f2 34; CHECK: vmsr fpscr 35; CHECK: mul 36define arm_aapcs_vfpcc i32 @f2(i32 %f, i32 %pscr_value) { 37entry: 38 %f.addr = alloca i32, align 4 39 store i32 %f, i32* %f.addr, align 4 40 call void asm sideeffect "vmsr fpscr,$1", "=*X,r"(i32* nonnull %f.addr, i32 %pscr_value) nounwind 41 %0 = load i32, i32* %f.addr, align 4 42 %mul = mul i32 %0, %0 43 ret i32 %mul 44} 45 46 47; int f3(int f, int pscr_value) { 48; asm volatile("vmsr fpscr,%0" : "=X" ((f)): "r" (pscr_value)); 49; return f+f; 50; } 51 52; typedef signed char int8_t; 53; typedef __attribute__((neon_vector_type(8))) int8_t int8x8_t; 54; void f3 (void) 55; { 56; int8x8_t vector_res_int8x8; 57; unsigned int fpscr; 58; asm volatile ("vmsr fpscr,%1" : "=X" ((vector_res_int8x8)) : "r" (fpscr)); 59; return vector_res_int8x8 * vector_res_int8x8; 60; } 61 62; CHECK-LABEL: f3 63; CHECK: vmsr fpscr 64; CHECK: vmul.i8 65define arm_aapcs_vfpcc <8 x i8> @f3() { 66entry: 67 %vector_res_int8x8 = alloca <8 x i8>, align 8 68 %0 = getelementptr inbounds <8 x i8>, <8 x i8>* %vector_res_int8x8, i32 0, i32 0 69 call void asm sideeffect "vmsr fpscr,$1", "=*X,r"(<8 x i8>* nonnull %vector_res_int8x8, i32 undef) nounwind 70 %1 = load <8 x i8>, <8 x i8>* %vector_res_int8x8, align 8 71 %mul = mul <8 x i8> %1, %1 72 ret <8 x i8> %mul 73} 74 75; We can emit integer constants. 76; We can get this from: 77; void f() { 78; int x = 2; 79; asm volatile ("add r0, r0, %0" : : "X" (x)); 80; } 81; 82; CHECK-LABEL: f4 83; CHECK: add r0, r0, #2 84define void @f4() { 85entry: 86 tail call void asm sideeffect "add r0, r0, $0", "X"(i32 2) 87 ret void 88} 89 90; We can emit function labels. This is equivalent to the following C code: 91; void f(void) { 92; void (*x)(void) = &foo; 93; asm volatile ("bl %0" : : "X" (x)); 94; } 95; CHECK-LABEL: f5 96; CHECK: bl f4 97define void @f5() { 98entry: 99 tail call void asm sideeffect "bl $0", "X"(void ()* nonnull @f4) 100 ret void 101} 102 103declare void @foo(...) 104 105; This tests the behavior of the X constraint when used on functions pointers, 106; or functions with a cast. In the first asm call we figure out that this 107; is a function pointer and emit the label. However, in the second asm call 108; we can't see through the bitcast and we end up having to lower this constraint 109; to something else. This is not ideal, but it is a correct behaviour according 110; to the definition of the X constraint. 111; 112; In this case (and other cases where we could have emitted something else), 113; what we're doing with the X constraint is not particularly useful either, 114; since the user could have used "r" in this situation for the same effect. 115 116; CHECK-LABEL: f6 117; CHECK: bl foo 118; CHECK: bl r 119 120define void @f6() nounwind { 121entry: 122 tail call void asm sideeffect "bl $0", "X"(void (...)* @foo) nounwind 123 tail call void asm sideeffect "bl $0", "X"(void (...)* bitcast (void ()* @f4 to void (...)*)) nounwind 124 ret void 125} 126 127; The following IR can be generated from C code with a function like: 128; void a() { 129; void* a = &&A; 130; asm volatile ("bl %0" : : "X" (a)); 131; A: 132; return; 133; } 134; 135; Ideally this would give the block address of bb, but it requires us to see 136; through blockaddress, which we can't do at the moment. This might break some 137; existing use cases where a user would expect to get a block label and instead 138; gets the block address in a register. However, note that according to the 139; "no constraints" definition this behaviour is correct (although not very nice). 140 141; CHECK-LABEL: f7 142; CHECK: bl 143define void @f7() { 144 call void asm sideeffect "bl $0", "X"( i8* blockaddress(@f7, %bb) ) 145 br label %bb 146bb: 147 ret void 148} 149 150; If we use a constraint "=*X", we should get a store back to *%x (in r0). 151; CHECK-LABEL: f8 152; CHECK: str r{{.*}}, [r0] 153define void @f8(i32 *%x) { 154entry: 155 tail call void asm sideeffect "add $0, r0, r0", "=*X"(i32 *%x) 156 ret void 157} 158