Subzero: Fold the load instruction into the next cast instruction.

tests_lit/llvm2ice_tests/load_cast.ll

Index: tests_lit/llvm2ice_tests/load_cast.ll
diff --git a/tests_lit/llvm2ice_tests/load_cast.ll b/tests_lit/llvm2ice_tests/load_cast.ll
new file mode 100644
index 0000000000000000000000000000000000000000..5395d04ff82f3ceef53a9494fc15d01d443411c6
--- /dev/null
+++ b/tests_lit/llvm2ice_tests/load_cast.ll
@@ -0,0 +1,266 @@
+; Tests desired and undesired folding of load instructions into cast
+; instructions.  The folding is only done when liveness analysis is performed,
+; so only O2 is tested.
+
+; RUN: %p2i --filetype=obj --disassemble -i %s --args -O2 | FileCheck %s
+
+; Not testing trunc, or 32-bit bitcast, because the lowered code uses pretty
+; much the same mov instructions regardless of whether folding is done.
+
+define internal i32 @zext_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i8*
+  %load = load i8* %addr, align 1
+  %result = zext i8 %load to i32
+  ret i32 %result
+}
+; CHECK-LABEL: zext_fold
+; CHECK: movzx {{.*}},BYTE PTR [{{.*}}+0xc8]
+
+define internal i32 @zext_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i8*
+  %load = load i8* %addr, align 1
+  %tmp1 = zext i8 %load to i32
+  %tmp2 = zext i8 %load to i32
+  %result = add i32 %tmp1, %tmp2
+  ret i32 %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: zext_nofold
+; CHECK-NOT: movzx {{.*}},BYTE PTR [{{.*}}+0xc8]
+
+define internal i32 @sext_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i8*
+  %load = load i8* %addr, align 1
+  %result = sext i8 %load to i32
+  ret i32 %result
+}
+; CHECK-LABEL: sext_fold
+; CHECK: movsx {{.*}},BYTE PTR [{{.*}}+0xc8]
+
+define internal i32 @sext_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i8*
+  %load = load i8* %addr, align 1
+  %tmp1 = sext i8 %load to i32
+  %tmp2 = sext i8 %load to i32
+  %result = add i32 %tmp1, %tmp2
+  ret i32 %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: sext_nofold
+; CHECK-NOT: movsx {{.*}},BYTE PTR [{{.*}}+0xc8]
+
+define internal float @fptrunc_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %result = fptrunc double %load to float
+  ret float %result
+}
+; CHECK-LABEL: fptrunc_fold
+; CHECK: cvtsd2ss {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal float @fptrunc_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %tmp1 = fptrunc double %load to float
+  %tmp2 = fptrunc double %load to float
+  %result = fadd float %tmp1, %tmp2
+  ret float %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: fptrunc_nofold
+; CHECK-NOT: cvtsd2ss {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal double @fpext_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to float*
+  %load = load float* %addr, align 4
+  %result = fpext float %load to double
+  ret double %result
+}
+; CHECK-LABEL: fpext_fold
+; CHECK: cvtss2sd {{.*}},DWORD PTR [{{.*}}+0xc8]
+
+define internal double @fpext_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to float*
+  %load = load float* %addr, align 4
+  %tmp1 = fpext float %load to double
+  %tmp2 = fpext float %load to double
+  %result = fadd double %tmp1, %tmp2
+  ret double %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: fpext_nofold
+; CHECK-NOT: cvtss2sd {{.*}},DWORD PTR [{{.*}}+0xc8]
+
+define internal i32 @fptoui_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %result = fptoui double %load to i16
+  %result2 = zext i16 %result to i32
+  ret i32 %result2
+}
+; CHECK-LABEL: fptoui_fold
+; CHECK: cvttsd2si {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal i32 @fptoui_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %tmp1 = fptoui double %load to i16
+  %tmp2 = fptoui double %load to i16
+  %result = add i16 %tmp1, %tmp2
+  %result2 = zext i16 %result to i32
+  ret i32 %result2
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: fptoui_nofold
+; CHECK-NOT: cvttsd2si {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal i32 @fptosi_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %result = fptosi double %load to i16
+  %result2 = zext i16 %result to i32
+  ret i32 %result2
+}
+; CHECK-LABEL: fptosi_fold
+; CHECK: cvttsd2si {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal i32 @fptosi_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %tmp1 = fptosi double %load to i16
+  %tmp2 = fptosi double %load to i16
+  %result = add i16 %tmp1, %tmp2
+  %result2 = zext i16 %result to i32
+  ret i32 %result2
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: fptosi_nofold
+; CHECK-NOT: cvttsd2si {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal double @uitofp_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i16*
+  %load = load i16* %addr, align 1
+  %result = uitofp i16 %load to double
+  ret double %result
+}
+; CHECK-LABEL: uitofp_fold
+; CHECK: movzx {{.*}},WORD PTR [{{.*}}+0xc8]
+
+define internal double @uitofp_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i16*
+  %load = load i16* %addr, align 1
+  %tmp1 = uitofp i16 %load to double
+  %tmp2 = uitofp i16 %load to double
+  %result = fadd double %tmp1, %tmp2
+  ret double %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: uitofp_nofold
+; CHECK-NOT: movzx {{.*}},WORD PTR [{{.*}}+0xc8]
+
+define internal double @sitofp_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i16*
+  %load = load i16* %addr, align 1
+  %result = sitofp i16 %load to double
+  ret double %result
+}
+; CHECK-LABEL: sitofp_fold
+; CHECK: movsx {{.*}},WORD PTR [{{.*}}+0xc8]
+
+define internal double @sitofp_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i16*
+  %load = load i16* %addr, align 1
+  %tmp1 = sitofp i16 %load to double
+  %tmp2 = sitofp i16 %load to double
+  %result = fadd double %tmp1, %tmp2
+  ret double %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: sitofp_nofold
+; CHECK-NOT: movsx {{.*}},WORD PTR [{{.*}}+0xc8]
+
+define internal double @bitcast_i64_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i64*
+  %load = load i64* %addr, align 1
+  %result = bitcast i64 %load to double
+  ret double %result
+}
+; CHECK-LABEL: bitcast_i64_fold
+; CHECK: movq {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal double @bitcast_i64_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to i64*
+  %load = load i64* %addr, align 1
+  %tmp1 = bitcast i64 %load to double
+  %tmp2 = bitcast i64 %load to double
+  %result = fadd double %tmp1, %tmp2
+  ret double %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: bitcast_i64_nofold
+; CHECK-NOT: movq {{.*}},QWORD PTR [{{.*}}+0xc8]
+
+define internal i64 @bitcast_double_fold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %result = bitcast double %load to i64
+  ret i64 %result
+}
+; CHECK-LABEL: bitcast_double_fold
+; CHECK-NOT: QWORD PTR
+; CHECK: mov {{.*}},DWORD PTR [{{.*}}+0xc8]
+; CHECK: mov {{.*}},DWORD PTR [{{.*}}+0xcc]
+; CHECK-NOT: QWORD PTR
+
+define internal i64 @bitcast_double_nofold(i32 %arg) {
+entry:
+  %ptr = add i32 %arg, 200
+  %addr = inttoptr i32 %ptr to double*
+  %load = load double* %addr, align 8
+  %tmp1 = bitcast double %load to i64
+  %tmp2 = bitcast double %load to i64
+  %result = add i64 %tmp1, %tmp2
+  ret i64 %result
+}
+; Test that load folding does not happen.
+; CHECK-LABEL: bitcast_double_nofold
+; CHECK: QWORD PTR
+; CHECK: QWORD PTR